EMERSON DAC Discharge Air Controller Instruction Manual
- June 12, 2024
- Emerson
Table of Contents
- EMERSON DAC Discharge Air Controller
- Discharge Air Controller (DAC) Installation and Operational Manual
- Contents
- Product Information
- Specifications
- Product Usage Instructions
- Introduction
- Wiring Types
- Software Overview
- Failure
- Supply Temperature Control
- Fan Control
- Outside Air Control
- Connections
- References
- Read User Manual Online (PDF format)
- Download This Manual (PDF format)
EMERSON DAC Discharge Air Controller
Discharge Air Controller (DAC) Installation and Operational Manual
- FW Version 1.04F05
- 026-1727 Rev 4
Emerson Digital Solutions Commercial and Residential Solutions
1065 Big Shanty Road NW, Suite 100
Email: ColdChain.TechnicalServices@Emerson.com
Contents
- INTRODUCTION
- 1.1. THE DAC’S I/O POINTS
- 1.2. INDEPENDENT SYSTEM CONTROL
- MOUNTING AND POWERING
- 2.1. INSTALLATION
- 2.2. POWERING THE DAC
- 2.2.1. Choosing Transformer Sizes
- 2.2.2. The DAC Power Wiring
- 2.2.3. Wire Types and Maximum Distances
- THE MODBUS NETWORK
- 3.2. MODBUS TERMINATION
- INPUT AND OUTPUT SETUP
- 4.1. THE DAC INPUTS
- 4.1.1. Wiring Analog Inputs on the DAC
- 4.1.2. Wiring Digital Inputs on the DAC
- 4.2. THE DAC OUTPUTS
- 4.2.1. Wiring Digital Loads on the DAC
- 4.2.2. Wiring Analog Outputs on the DAC
Product Information
The Discharge Air Controller (DAC) is a device used for independent system control in commercial and residential solutions. It is manufactured by Emerson Digital Solutions and is designed to regulate and monitor the discharge air in a controlled environment.
Specifications
| FW Version | 1.04F05 |
|---|---|
| Model Number | 026-1727 Rev 4 |
| Manufacturer | Emerson Digital Solutions |
| Address | 1065 Big Shanty Road NW, Suite 100 |
| Website | www.climate.emerson.com |
| ColdChain.TechnicalServices@Emerson.com |
Product Usage Instructions
Mounting and Powering
To install the DAC, follow the steps below:
- Choose a suitable location for mounting the DAC.
- Ensure proper installation of the DAC according to the provided instructions.
- Power the DAC using an appropriate transformer.
- Refer to the manual for guidance on choosing transformer sizes.
- Follow the DAC power wiring instructions for proper connection.
- Use the recommended wire types and adhere to the maximum distance guidelines.
The Modbus Network
The DAC is compatible with the Modbus network. Ensure proper termination of
the Modbus network for optimal performance.
Input and Output Setup
The DAC has various inputs and outputs that can be configured. Follow these
instructions for setting up the inputs and outputs:
The DAC Inputs
Wiring analog and digital inputs on the DAC:
- For analog inputs, refer to the wiring instructions provided in the manual.
- For digital inputs, follow the wiring instructions provided in the manual.
The DAC Outputs
Wiring digital loads and analog outputs on the DAC:
- For wiring digital loads, refer to the instructions provided in the manual.
- For wiring analog outputs, follow the instructions provided in the manual.
Discharge Air Controller (DAC) Installation and Operational Manual
FW Version 1.04F05
026-1727 Rev 4
Emerson Digital Solutions Commercial and Residential Solutions 1065 Big Shanty
Road NW, Suite 100
Kennesaw, GA 30144 770-425-2724 ·
1-800-829-2724
www.climate.emerson.com Email:
ColdChain.TechnicalServices@Emerson.com
Introduction
The Discharge Air Controller (DAC) (P/N 818-9001) is a packaged HVAC distributed controller designed to be used with an Emerson supervisory controller. Site Supervisor, E3 and E2 BX building control systems support Modbus communication to the DAC and include the HVAC Zone application, providing control coordination of collocated DACs. The DAC is capable of controlling heat and cool stages, fans, dehumidification devices, and economizers using on-board I/O and control algorithms, as well as monitor and interact with other building control systems and peripherals (such as smoke alarms and CO2 sensors).
1.1. The DAC’s I/O Points
The compact size of the DAC allows technicians to field-mount the DAC in a
rooftop unit or enclosure close to it, allowing for local connection of
sensors and transducers. The board has 10 analog inputs and 20 digital inputs,
with default configurations preloaded for quick connection to space
temperature sensors, supply and return air temperature sensors, and fan
proofs. Its 15 relay outputs, rated 2.0 amps max, are used for activating and
deactivating fans, heat and cool stages, economizers, and other systems or
devices. Its 6 analog outputs may be used for air damper, modulated heat and
cool control, and variable-speed fan control.
Figure 1-1 – DAC
The DAC supports local physical inputs and outputs and communicates with the
E2 controller (version 3.00 and higher) via the RS485 MODBUS network.
The E2 will support a maximum of 32 instances of the DAC to be added to a
BX-300 or CX-300. The E2 will support a maximum of 50 DAC devices on a BX-400
or CX-400.
The DAC supports 15 relay outputs, 6 analog outputs, 10 analog inputs, and 10
digital inputs.
1.2. Independent System Control
The DAC can control a rooftop unit independently without the need of a central
controller (such as the E2 BX Building Controller). However, the DAC is
designed to interface with an E2 to allow it to work with other DACs together
to control large zones. Networking the DAC to a central controller also allows
you to view status on E2 and UltraSite32 Site Manager status screens, report
alarms, and log point values.
The DAC’s configuration can only be programmed through the E2 front panel.
The DAC was designed to be used with an Emerson supervisory controller, and
one of these supervisory controllers is the only method for configuring the
DAC. If there is no supervisory controller, the DAC can be standalone, but in
reduced capacity. However, if the supervisory controller goes offline, the DAC
operates standalone using the last configuration received from it. While in
standalone, the DAC will continue to control heating/cooling but will remain
in occupied mode only (no scheduling) until communication is reestablished.
The supervisory controller maintains the occupancy schedule and is responsible
for sending the occupancy signal over ModBus to the DAC.
The DAC’s I/O Points
Introduction · 1
2 Mounting and Powering
The DAC is usually mounted by the HVAC equipment manufacturer. Therefore, the
installer need only make the necessary connections between the boards and the
site controller(s). In some instances, an installer may be required to mount
the DAC. There are no restrictions on the location of the DAC; however, the
controller should be mounted in a location protected from moisture. Typically,
mounting inside the electrical control panel of a package unit is acceptable.
If there is no room to mount the controller inside the HVAC unit, it may be
mounted inside a weatherproof enclosure on the outside of the unit.
2.1. Installation
The DAC uses a DIN mount installation.
Figure 2-1 – DIN Mounting
Mount:
On a DIN rail (EN 50022, DIN 43880) Fastened with screws via the removable plastic flaps.
Material:
PC-ABS Thermoplastic
Self-extinguishing: V0 (UL94)
Comparative Tracking Index (CTI):
300V
Color:
White
Table 2-1 – DAC Enclosure Specifications
2.2. Powering the DAC
Emerson supplies a wide variety of 24VAC transformers with varying sizes
without center taps. Table 2-2 shows the transformer sizes and are noncenter-
tapped.
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2.2.1. Choosing Transformer Sizes
The transformer used to power the DAC should have at least a 20VA rating. The
DAC should not share a transformer with any other devices.
Transformer P/N
VA Rating
Primary Voltage
640-0041 640-0042
50 VA 50 VA
110 VAC 220 VAC
Table 2-2 – Transformers Compatible with DAC
2.2.2. The DAC Power Wiring
The DACs can be powered by one of the 50VA noncenter-tapped transformers
listed in Table 2-2. Figure 2-2 shows how to wire the transformers to the DAC
boards.
Neither side of the secondary should be connected to ground. Also, do not
connect the center tap (if provided on the transformer) to ground. The entire
secondary of the transformer should be isolated from any ground.
2.2.3. Wire Types and Maximum Distances
For powering I/O boards, use only the listed wire types in Table 2-3. Two-
conductor non-shielded cables are the recommended wire for connecting the
transformer to the DAC. Shielded cable should not be used for power wiring.
The center tap should be left disconnected, if present on the transformer.
Power Wiring Types
14 AWG 18 AWG
Belden 9495 Belden 9495
Table 2-3 – Power Wiring Types
The wire length from the transformer determines the type wire gauge used. In
most cases, the distance between the DAC and the transformer that supplies
power to it is not enough to be of concern; however, it is very important NOT
to exceed this maximum wire length or the controller will not operate
correctly.
Use these formulas to determine if the wire gauge you are using fits within
specification:
14 AWG: Feet = 1920/VA 18 AWG: Feet = 739/VA (VA is the total VA rating of the controller) For example, if you had an 80 VA load: 14 AWG: 24 ft. 18 AWG: 9 ft. (rounded down)
Figure 2-2 – Non-Center-Tapped Transformer Wiring
Table 2-4 – Power Wire Lengths
Sensors requiring 24VAC should not be powered from the same transformer
powering the input board. Any devices that will be connected to the DAC’s
inputs or outputs must be powered with a separate 24VAC transformer.
Powering the DAC
Mounting and Powering · 3
3 The MODBUS Network
Although the DAC can operate as a stand-alone controller, it relies on an E2
unit for advanced features such as remote dial-in/dial-out, logging, and alarm
control. The DAC uses an RS485 network connection to communicate with E2 site
controllers.
3.1. Wiring Types
Emerson specs Belden #8761 shielded twisted pair cables for use as MODBUS
wiring (or Belden #82761 and Belden #88761 for plenum installations).
If the recommended cable is not available in your area, be sure the wiring
meets or exceeds the
following specs:
Shielded?
Yes
Conductor Type Twisted Pair
Gauge
18 – 24 AWG
Capacitance between 31 pF/ft or less
signal wires
(9.45 m) or less
Capacitance between 59 pF/ft or less signal and shield (17.98 m) or less
Nominal Impedance 12050
3.1.1. Daisy Chains
Connect the MODBUS network cable to the three-terminal connector on the E2 COM
port you wish to assign as MODBUS. Reverse the polarity of +/- on the RS485
cable between the E2 and the DAC.
Figure 3-1 – MODBUS Networking 4 · Discharge Air Controller (DAC) Manual
026-1727 Rev 4
3.1.2. Network Addressing Visograph
The network address makes a board unique from other boards on the network of
the same type. This allows the site controller to find it and communicate with
it easily.
The network address of the DAC is set using add-on devices called visographs
(P/N 318-7272).
3.1.2.1. Connecting the Visograph
The Visograph is connected with a 3-wire connection on pins 103, 104, and 105.
Figure 3-3 – Visograph Buttons
3.1.2.3. Setting the MODBUS Address
Boards of the same type are typically numbered in sequence, starting with one
and continuing with two, three, and so forth.
Note, all DAC setpoints must be viewed/modified through the user interface of
the connected supervisory controller. The Visograph interface is intended to
be used primarily to check unit status and perform temporary output overrides.
Configuration of the physical inputs and outputs is also possible.
Figure 3-2 – Network ID Settings
CAUTION! The DAC may be damaged if the wires are crossed when connecting the
visograph, especially if pin 103 (Vnr) is accidentally connected to + or
3.1.2.2. Visograph Navigation
· Six menu items are available to choose from. · Shows current MODBUS address
and
application version (see Figure 3-4). · Press corresponding button along the
bottom
(T1-T6) to navigate to desired item.
Figure 3-4 – Main Menu – Press 5 to Set Address
1. Press 5 – Controller Info on the main menu to see Controller Info screen.
Wiring Types
The MODBUS Network · 5
The first field highlighted by the cursor is the Modbus Address. To change the address:
4 Input and Output Setup
4.1. The DAC Inputs
Figure 3-5 – Controller Info – Modbus Address 2. Press the ENTER key (T3). The
address field should start blinking. 3. Using the UP and DOWN arrows (T4 and
T5), change the address to the desired value. 4. Press ENTER to save new
address.The address field should stop blinking. 5. Press MENU (T1) to go back
to main menu.
NOTE: When the MODBUS address is changed, the DAC will automatically reboot.
3.1.2.3.1. Versions The DAC and Visograph versions are also shown on the
Controller Info screen. If the Visograph version shown is not the most recent,
set the Reload Display field to Yes. This will cause the display to download
the latest screens contained in the DAC.
3.2. MODBUS Termination
The DAC has on-board termination capability. A single termination jumper is
located next to the RS485 slave connector. If the DAC is located at the
physical end of the MODBUS network, the termination jumper should be applied.
Figure 4-1 – DAC Input Locations
The DAC will be able to use input data from either physical or network inputs.
The DAC has connections to analog and digital sensors, transducers, switches,
and other input types typically used in a rooftop HVAC unit application. The
input type and function for each point must be programmed in the DAC software
by the installer.
The DAC application will support the following analog inputs:
Analog Input Type
Description
CO2 Level
Local or Network CO2 Level Network
Duct Pressure Physical Local Duct Static Pressure Sensor
Inside Humidity Local or Network Inside Network Humidity
Mixed Air Temp Physical Local Mixed Air Temperature Sensor
OAH
Local or Outside Humidity Network
Table 4-1 – DAC Analog Inputs
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Analog Input Type
Description
OAT
Local or Outside Air
Network Temperature
Return Air Temp Local
Local Return Air Temperature Sensor
Setpoint Reset Local (slider)
Local Setpoint Reset Slider
Space Temp (2) Local
Local Space Temperature Sensor
Suction Pressure Local (2)
Local Suction Pressure Sensor (used for Dehumidification control with Digital Scroll Compressors)
Supply Temp
Local
Local Supply Air Temperature (mandatory sensor required for control)
Zone Temp
Network Network Space (DAC Temperature only)
Auxiliary (2)
Local
Satellite Inputs used by E2
Table 4-1 – DAC Analog Inputs
The DAC will support the following digital inputs:
NOTE: The Digital Inputs of the DAC are predefined and cannot be changed.
Digital Input
Point Number
Description
VFD Alarm
6
Variable Frequency
Drive Alarm
Exhaust Hood
7
Local Exhaust Hood
On
Sensor
Bypass to Occ
8
Local Occupancy
Bypass Switch
Auxiliary A
9
Satellite Inputs used
by E2
Auxiliary B
10
Satellite Inputs used
by E2
Table 4-2 – DAC Digital Inputs
4.1.1. Wiring Analog Inputs on the DAC
The analog inputs are located on the same connector as the controller power supply.
Figure 4-2 – Analog Input Connectors
The DAC provides separate input commons depending on the type of sensor
connected. For temperature probes, all commons should be wired to PbC on
terminal 7. For voltage output transducers, all commons should be wired to GND
on terminal 8.
Digital Input
Point Number
Fan Proof
1
Smoke
2
Detector
Dirty Filter
3
Freeze Stat
4
Phase Loss
5
Table 4-2 – DAC Digital Inputs
Description
Local Fan Proof Sensor Local Smoke Detector Local Dirty Filter Sensor Local
Freeze Stat Local Phase Loss Sensor
Figure 4-3 – Temperature Probe Wiring Figure 4-4 – Transducer Wiring for +5V Powered Devices
The DAC Inputs
Input and Output Setup · 7
Figure 4-5 – Transducer Wiring for +12V Powered Devices
CAUTION! Mis-wiring a sensor to the wrong common can result in damage to the
DAC.
CAUTION! Any inputs that are powered with a voltage that differs from that
supplied by the DAC (+12V or +5V) must be powered separately with another
transformer in order to prevent the inputs from malfunctioning or being
damaged. Do not use the same secondary of the controller’s power to power the
sensors.
Terminal Number on Connector
Name
1
24VAC Supply –
2
Probe Input 1
3
Probe Input 2
4
Probe Input 3
5
Probe Input 4
6
Probe Input 5
7
Temperature Common
8
GND
9
24VAC Supply +
10
Probe Input 6
11
Probe Input 7
12
Probe Input 8
13
Probe Input 9
14
Probe Input 10
15
+5VDC
16
+12VDC
Table 4-3 – Analog Input Connector Terminal Numbers
4.1.2. Wiring Digital Inputs on the DAC
The digital inputs are located on a separate 22-pin connector.
Figure 4-6 – Digital Input Connectors
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The DAC hardware provides a maximum of 20 opto-insulated digital inputs. However, for the DAC, only the first ten inputs are currently available for use (see Table 4-2). All digital inputs are voltage-free and are intended to have dry contact devices connected.
Figure 4-7 – Digital Input Wiring
Figure 4-8 – Digital Inputs
Terminal Number on Connector
Name
40
Digital Input 1
41
Digital Input 2
42
Digital Input 3
43
Digital Input 4
44
Digital Input 5
45
Digital Input 6
46
Digital Input 7
47
Digital Input 8
Table 4-4 – Digital Input Connector Terminal Numbers
The DAC Inputs
48
Digital Input 9
49
Digital Input 10
50
51
Digital Input 11
(unsupported)
52
Digital Input 12
(unsupported)
53
Digital Input 13
(unsupported)
54
Digital Input 1
(unsupported)
55
Digital Input 15
(unsupported)
56
Digital Input 16
(unsupported)
57
Digital Input 17
(unsupported)
58
Digital Input 18
(unsupported)
59
Digital Input 19
(unsupported)
60
Digital Input 20
(unsupported)
61
Volt-free Digital Common
Table 4-4 – Digital Input Connector Terminal Numbers
Input and Output Setup · 9
4.2. The DAC Outputs
Relay Outputs
Analog Outputs
Figure 4-9 – DAC Output Locations
The DAC has 15 relay outputs for connection to all loads that are typically
present for a rooftop unit. The relay output type and function for each point
must be programmed in the DAC software by the installer.
The DAC supports the following relay outputs:
Relay Output
Description
Alarm Active
Alarm Active Output
Cool Stage 1-4
Cool Stage Output
Dehumidifier Digital Dehumidification Active
Econ Enable
Economization Enabled
Fan Enable
Fan Enable
Primary Heat Stage 1- Primary Heat Stage Output 2
Secondary Heat Stage Secondary Heat Stage
1-2
Output
Reversing Valve
Heat Pump Reversing Valve Output
Auxiliary (2)
Satellite Outputs Controlled by E2
Reheat
Reheat Output
Table 4-5 – DAC Relay Outputs
The DAC supports the following analog outputs:
Analog Output
Description
Mod Fan (VS)
Modulating Fan
Mod Cool (2)
Modulating Cool Stages (including Digital Scroll compressors)
Mod Heat
Modulating Heat
Mod Outdoor Air Damper
Modulating Outdoor Air Damper
Mod Return Air Bypass
Modulating Return Air Bypass
Mod Return Air Damper
Modulating Return Air Damper
Mod VAV Bypass Modulating Variable Air
Damper
Volume Bypass Damper
Supply Air SP Reset Supply Air Setpoint Reset
Auxiliary (2)
Satellite Outputs Controlled by E2
Table 4-6 – DAC Analog Outputs
For both relay and analog outputs, the DAC will drive physical points as well
as send the current output value over MODBUS to E2.
4.2.1. Wiring Digital Loads on the DAC
The digital output relays are located across four separate connectors along the top side of the DAC.
Figure 4-10 – Digital Load Connectors
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The normally-open relay outputs on each connector share the same common and are not fused. Make sure to use the same voltage for all loads connected to the relays.
4.2.2. Wiring Analog Outputs on the DAC
The analog outputs are located on a separate 12-pin connector.
Figure 4-11 – Relay Output Wiring
Terminal Number on Connector
Name
70
Relay 1
71
Common for Relays 1-3
72
Relay 2
73
Relay 3
76
Relay 4
77
Relay 5
78
Relay 6
79
Relay 7
80
Common for Relays 4-8
81
Relay 8
84
Relay 9
85
Relay 10
86
Common for Relays 9-10
87
Relay 11
88
Relay 12
89
Relay 13
90
Common for Relays 11-15
91
Relay 14
92
Relay 15
93
Table 4-7 -Digital Relay Output Connector Terminal Numbers
Figure 4-12 – Analog Outputs Connectors
The DAC provides six opto-isolated analog outputs. Because the analog outputs
are opto-isolated, they must be separately powered by a 24V supply. For the
outputs to function properly, connect a 24VAC supply (separate from the
controller’s main supply) to terminals 28 and 29. The same transformer used to
power the devices controlled by the analog outputs (e.g., damper actuator) may
be used to supply power to terminals 28 and 29.
Figure 4-13 – Analog Output Wiring
CAUTION! The devices controlled by these analog outputs must be powered
separately with another transformer (do not use the same secondary of the
controller’s power) in order to prevent the outputs from malfunctioning or
being damaged.
The DAC Outputs
Input and Output Setup · 11
Terminal Number on Connector
Name
21
Analog Output 1
22
Analog Output 2
23
Analog Output 3
24
Analog Output 4
25
Analog Out Common
26
Analog Output 5
27
Analog Output 6
28
24VAC or 24VDC(-)
29
24VAC or 24VDC(+)
30
Analog Out Common
Table 4-8 -Digital Relay Output Connector Terminal Numbers
12 · Discharge Air Controller (DAC) Manual
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5 Wiring Connection to Site Supervisor
Figure 5-1 – Site Supervisor Wiring
The DAC Outputs
Wiring Connection to Site Supervisor · 13
6 DAC Status LEDs
When a DAC board is powered up, you will be able to determine the operating
status of the board by observing its status LEDs.
Figure 6-1 – DAC Status LED Locations
6.1. PWR ON LED
The PWR ON LED stays on continuously to show that the board is powered and
operational. If this light is dark, the board has likely lost power.
6.2. Tx and Rx LEDs
The Tx and Rx LEDs indicate when the DAC is sending or receiving messages on
the RS485 network.
The Tx LED blinks once every time the DAC sends a response to the E2. The Rx
LED blinks once when the DAC receives a message.
If the DAC is connected to the network and set up to communicate with the
controller, you should see these lights blinking regularly. If they do not
blink regularly, there may be a problem with the network.
6.3. LED1 Network Status
The amber colored LED1 indicates whether the DAC is online or offline with the
E2. When the DAC is online, the LED1 will turn on for one second and off for
one second. However, if the DAC is offline, the LED1 will turn on for half a
second and off for half a second (blink twice as fast). When the DAC is
offline, it reverts to standalone control, using only the locally connected
inputs to control the HVAC unit. In this state, the controller reverts to an
Occupied mode.
6.4. ALARM LED Status
When the red ALARM LED is turned on, the DAC has an active alarm. When in this
state, the Alarm relay output (if defined) will turn on. Check the E2 advisory
log for details on the type of alarm.
14 · Discharge Air Controller (DAC) Manual
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Software Overview
The DAC maintains space temperature setpoints by modulating heating or cooling stages to maintain a desired supply air temperature. For this reason, a supply air temperature sensor must be connected to the controller. The desired supply air temperature is primarily determined by a setpoint and can be automatically adjusted based on changes in building load.
Also, VAV mode does not require a local space sensor to be connected to the
controller. Instead, the system terminal load is calculated by the E2 and is
sent over the network to the DAC so the operational mode can be determined.
Note that the primary control of heating and cooling stages using the supply
air temperature sensor is identical for either CAV or VAV mode.
7.2. Operational Modes
7.1. Application Mode
The DAC supports packaged HVAC control in either Constant Air Volume (CAV) or
Variable Air Volume (VAV) applications. The main difference between the two
modes is how the variable speed fan will be controlled. When CAV is selected,
the variable speed fan is modulated based on the number of heating or cooling
stages that are currently active. When VAV is selected, the variable speed fan
modulates to maintain a static duct pressure. See Section 7.5., Fan Control
for more details.
The DAC will be in one of nine possible modes of operation at any given time. All modes have different priorities so if conditions warrant two modes to be operational at the same time, one of the modes will win and become active. In the table, the modes are shown in ascending priority with the exception of Cooling and Dehum. For example, Idle is the lowest priority and Emergency Shutdown is the highest priority, but if both cooling and dehumidification are called for, the larger of the two calculated loads will take priority and activate the proper mode of operation.
Corresponding Site Manager
Mode
Operating Mode
Description
Outputs Active
0
Idle
Default mode if no other modes are active None
1
Ventilation Space air recirculation only
Indoor Fan
2
CO2 Purge Max CO2 level reached and fresh air Indoor Fan, Outdoor Air
must be brought in to building
Damper
3
Economizing Outdoor air free cooling active
Indoor Fan, Outdoor Air
Damper
4
Make-up Air Exhaust Fan detected and make-up air Indoor Fan, Outdoor Air
must be brought in to building
Damper
5
Heating
Heating is active
Indoor Fan, Heat Stages, Modulating Heat
6
Cooling
Cooling is active
Indoor Fan, Cool Stages (Fixed or Modulating),
7
Dehum
Dehumidification is active
Indoor Fan, Cool Stages or
Dehum Output, Reheat Output
8
Emergency One of the following is active: Smoke None
Shutdown Detected, Phase Loss Active, Fan Proof
Failure
Table 7-1 – DAC Operational Modes with Corresponding Site Manager Mode
Application Mode
Software Overview · 15
7.3. Space Temperature Control
There are two active space temperature setpoints in a DAC: a cooling setpoint
and a heating setpoint. In general, when the input rises above the cooling
setpoint, cooling mode begins, and when the input falls below the heating
setpoint, heating mode begins.
7.3.1. Terminal Load Calculation
As the space temperature rises above the active cooling setpoint, or falls
below the active heating setpoint, the system’s terminal load will increase,
either positively for cooling, or negatively for heating. The terminal load
can range from -100% to +100%, where all negative values indicate a demand for
heating and all positive values indicate a demand for cooling.
Figure 7-1 – Terminal Load Graph
When the terminal load rises above 20%, cooling mode will be activated.
Conversely, when the terminal load falls below -20%, heating mode will be
activated. Once activated, both cooling and heating modes will deactivate if
the terminal loads goes back to 0%.
7.4. Supply Temperature Control
The DAC will determine the active supply air temperature setpoint based on
whether heating or cooling is active as well as the amount of terminal load.
When heating mode is active, the controller will use the supply temperature
heating setpoint as the active supply temperature setpoint. Heat stages will
be turned on to maintain the supply air temperature at the
active setpoint. Conversely, when cooling mode is active, the controller will
use the supply temperature cooling setpoint as the active supply temperature
setpoint. Cool stages will be turned on to maintain the supply air temperature
at the active setpoint.
7.4.1. Supply Air Setpoint Reset
The active supply air setpoint may be automatically adjusted (reset) based on
the heating or cooling terminal load present. The active setpoint will be
increased or decreased up to the maximum amount specified by the heating and
cooling reset setpoints. The maximum amount will be used when the terminal
load reaches +100% for cooling and -100% for heating.
7.4.2. Cooling Mode
The DAC supports both staged and modulating mechanical cooling devices.
Modulating devices are treated as a cooling stage in the case of a unit having
a mixture of fixed and variable capacity compressors.
7.4.2.1. Staged Cooling
Up to four stages of cooling can be used. Each compressor stage can be
configured to be fixed size, digital scroll, VS, double size, or heat pump.
The fixed size and heat pump compressors assume a fixed capacity while the
digital scroll and VS compressors assume a modulating capability. The double
size compressor indicates a fixed compressor which is double in capacity
compared to the other fixed compressors.
NOTE: The application supports a maximum of two digital/VS compressor stages.
When a compressor stage is defined as a heat pump, it will turn on for both
cooling and heating. A reversing valve must also be used and can be defined as
active cooling or active heating.
7.4.2.1.1. Staging On
When cooling is required, the cool stages will stage on if the current supply
air temperature is above the active supply air cooling setpoint. The lowest
stage that is off will be turned on first. Additional stages will be brought
on according to the Cool On-Delay setpoint. A cooling stage will not be turned
on unless it has satisfied its minimum off time.
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7.4.2.1.2. Staging Off
When the current supply air temperature drops below the active supply air
cooling setpoint minus the Cool Stage Deadband, cooling stages will begin to
stage off. The highest stage that is currently on will be turned off first.
Additional stages will be turned off according to the Cool Off-Delay
parameter. A cooling stage will not be turned off unless it has satisfied its
minimum run time.
7.4.2.2. Modulating Cooling
Up to two cooling stages may be defined as variable capacity (VS or digital
scroll). Variable capacity stages should be assigned the lowest numbered cool
stages. As with fixed capacity staging, variable capacity stages will be
activated if the supply air temperature is above the active supply air cooling
setpoint. However, the next higher stage after a variable capacity stage will
start its On-Delay only after the variable stage is at its maximum capacity.
Likewise, the next lower stage before a variable capacity stage will start its
Off-Delay only after the variable stage is at its minimum capacity.
When a variable capacity compressor is activated, it will modulate to maintain
the supply air temperature at the active supply air cooling setpoint. A PID
loop will be used to determine the capacity output.
If the first two stages are both variable capacity compressors, the lower
stage will turn on first and ramp up. When the second modulating stage is
activated, the first modulating stage will remain at its maximum percent while
the PID loop controls the second modulating stage. Once the second modulating
stage has turned off, the first modulating stage will be allowed to modulate
again.
The variable capacity compressors have both minimum and maximum capacity
setpoints. In the case of multiple modulating stages, all stages will use the
same minimum and maximum settings.
7.4.2.3. Cooling OAT Lockout
Cooling will only be allowed when the outside air temperature is above the
cooling lockout temperature setpoint. If the outside temperature falls below
this setpoint, cooling will be deactivated. Cooling will only be re-enabled
when the outside temperature rises back above the lockout setpoint plus 2°F.
7.4.3. Heating Mode
The DAC supports both staged and modulating mechanical heating devices. A
modulating device, such as a hot water valve, is treated as a heating stage in
the case of a unit having a mixture of fixed and modulating heating sources.
7.4.3.1. Staged Heating
Up to two stages of primary heating and two stages of secondary heating can be
defined for a total of four heating stages. Lower operating cost heat stages,
e.g., reclaim heat, should be connected to the primary heat outputs on the
controller. Higher operating cost heat stages, e.g., gas or electric heat,
should be connected to the secondary heat outputs. The controller will always
activate all primary heat sources before activating secondary heat sources.
7.4.3.1.1. Staging On
When heating is required, the heat stages will stage on if the supply air
temperature is below the active supply air heating setpoint. The lowest
primary heat stage that is off will be turned on first. Additional primary
stages will be brought on according to the Heat On-Delay setpoint as long as
the supply temperature remains below the active supply temperature heating
setpoint. A heating stage will not be turned on unless it has satisfied its
minimum off time. Once all primary heating stages are on, secondary heating
stages will begin to stage on in the same manner as the primary heating
stages.
7.4.3.1.2. Staging Off
When the supply air temperature rises above the active supply air heating
setpoint plus the Heat Stage Deadband, heating stages will begin to stage off.
The highest active secondary heating stage will be turned off first.
Additional secondary stages will be turned off according to the Heat Off-Delay
setpoint as long as the supply temperature remains above the supply
temperature heating setpoint plus the Heat Stage Deadband. A heating stage
will not be turned off unless it has satisfied its minimum run time as
specified by the parameter Heat Min On. Once all secondary heating stages are
off, primary heating stages will begin to stage off in the same manner as the
secondary heating stages.
Supply Temperature Control
Software Overview · 17
7.4.3.2. Modulating Heating
In addition to the primary and secondary heat stages, the DAC supports one
modulating heating output. This modulating output must be classified as either
a primary or secondary heat source.
7.4.3.2.1. Primary Mod Heat
If the modulating heat output is classified as a primary heating source, it
will be activated before any other primary heat stages when the application
calls for heating. Once activated, the modulating heat output will modulate to
maintain the supply air temperature at the active supply air heating setpoint.
A PID loop will be used to determine the capacity output. If the modulating
heat output reaches 100% and remains there for the Heat On-Delay period, the
first primary heating stage will be activated. Additional primary heating
stages will be brought on according to the Heat On-Delay as long as the
modulating heating output remains at 100%. No additional stages of heating
will be brought on while the modulating heat output is less than 100%. When
all primary heating stages have been activated, secondary heat stages will be
allowed to stage on similar to the primary heating stages.
Secondary and primary heat stages will be sequentially turned off as demand
for heating is reduced. The highest secondary stage will turn off after the
modulating heat output has been at minimum capacity for the Heat Off-Delay.
Additional heat stages will be turned off in the same way.
will be used to determine the capacity output. If the modulating heat output
reaches 100% and stays there for the Heat On-Delay period, the first secondary
heating stage will be activated. Additional secondary heating stages will be
brought on according to the Heat On-Delay as long as the modulating heating
output remains at 100%. No additional stages of heating will be activated
while the modulating heat output is less than 100%.
Secondary heat stages will be sequentially turned off as demand for heating is
reduced. The highest secondary stage will turn off after the modulating heat
output has been at minimum capacity for the Heat Off-Delay period. Additional
heat stages will be turned off in the same way. Once all secondary heat stages
are off, the modulating heat output will remain on until it goes to minimum
capacity and stays there for at least the Heat Off-Delay period. After this
time, the modulating heat output will turn off, leaving only the primary heat
stages still active. The primary heat stages will then stage off as previously
described.
Figure 7-3 – Heat Staging Secondary Graph
7.4.3.3. Heating OAT Lockout
Heating will only be allowed when the outside air temperature is below the
heat lockout temperature setpoint. If the outside temperature rises above this
setpoint, heating will be deactivated. Heating will only be re-enabled when
the outside temperature falls 2°F below the lockout setpoint.
Figure 7-2 – Heat Staging Primary Graph
7.4.3.2.2. Secondary Mod Heat
If the modulating heat output is classified as a secondary heating source, it
will be activated only after all primary heat stages have staged on, but
before any defined secondary heat stages are activated. Once activated, the
modulating heat output will modulate to maintain the supply air temperature at
the active supply air heating setpoint. A PID loop
7.5. Fan Control
The DAC supports control of either a single speed fan or a variable speed (VS)
indoor fan. The method used to control the fan depends on the application mode
setting (CAV or VAV see Section 7.1., Application Mode for more
information).
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7.5.1. CAV Mode
The indoor fan will be controlled in one of three ways:
· Continuous The fan is always on, even when the controller is not in
heating, cooling, or dehumidification mode. In variable speed fan control,
when heating or cooling is not active, the fan will be ON at a fixed, user-
defined idle speed.
· Auto The fan is only on when the controller is in heating, cooling,
dehumidification, or outside air damper operation mode.
· Summer ON, Winter Auto (SOWA) This mode allows the fan to operate in
Continuous mode during the summer months and in Auto mode during the winter
months (based on the season passed to the DAC from the E2 controller).
If desired, activation and deactivation delays may be set up for the DAC
application for both heating and cooling mode.
7.5.1.1. Variable-Speed Fan Control in CAV
When using a variable-speed fan, each heat and cool stage has its own
individual VS fan speed setpoint. When one or more stages are active, the DAC
will look at the setpoints of all active stages and operate the VS fan at the
highest setpoint value.
Example: A DAC is controlling two heat stages. Heat stage #1’s VS fan setpoint
is 50%, and Heat stage #2’s VS fan setpoint is 100%. When heating mode first
begins and the heat stage #1 becomes ACTIVE, the fan will increase speed from
idle to 50%. When heat stage #2 is activated for more heating, the DAC looks
at both heat stage #1 and #2’s setpoints, determines that the highest setpoint
belongs to stage #2 (100%), and increases the fan speed to 100%.
7.5.1.1.1. Economization VS Fan Speed
Because the controller treats economization separately from mechanical
cooling, the economization damper has its own fan speed setpoint. When
economization is enabled and no other cooling stages are active, the VS fan
will operate at the economization fan speed setpoint.
7.5.1.1.2. CO2 Purge VS Fan Speed
When a CO2 purge is active and heating and cooling are not active, the DAC
will operate the VS fan at the CO2 Purge VS Fan Speed setpoint.
7.5.1.1.3. Make-up Air Offset VS Fan Speed
When make-up air is active, the current VS fan speed will be increased by the
Make-up Air Offset% setpoint.
7.5.1.1.4. Idle VS Fan Speed
When using the “Continuous” fan mode, the DAC will use the Idle VS Fan Speed
setpoint when no cooling or heating stages are active.
7.5.1.1.5. Dehumidification Offset
During dehumidification, a lower VS fan speed is typically desired. The DAC
uses a dehumidification offset parameter to achieve this. When an offset
greater that 0% is specified in the DAC, the offset is subtracted from the
final VS fan speed when dehumidification is active.
For example, if the dehumidification offset is 5%, and cool stage 1’s VS fan
speed setpoint is 50%, when dehumidification is active with one cooling stage
ON, the VS fan speed will be adjusted down to 45% (50% – 5%). If a second cool
stage with a setpoint of 100% were to turn ON, the VS fan speed would increase
to 95% (100% – 5%).
7.5.1.1.6. VAV Mode
For VAV applications, the supply duct static pressure must be controlled to
avoid over pressurization of the ductwork. The DAC can support control of the
duct static pressure using either a variable speed fan or a single speed fan
in conjunction with a bypass damper.
7.5.1.2. Single Speed with Bypass Damper
The single speed fan will activate as described in Section 7.5.1., CAV Mode.
When the fan is active, the duct static pressure will be controlled using a
modulating bypass damper. When the bypass damper is at 0%, it is considered
fully closed, meaning no supply air is bypassed to the return. As the static
pressure in the duct rises above the static pressure setpoint, the bypass
damper will begin to open based on the output from a PID loop (direct acting),
thus relieving the pressure in the duct.
7.5.1.3. Variable-Speed Fan Control in VAV
The variable-speed fan will activate as described in Section 7.5.1., CAV Mode
Once active, the speed of the fan will modulate to maintain the duct pressure
setpoint. As the static pressure falls below the setpoint, the VS fan will
increase in speed (reverse
Fan Control
Software Overview · 19
acting). A user parameter will specify the minimum speed that the VS fan is
allowed to operate at when active.
7.5.2. Fan Proofing
For both CAV and VAV modes, fan proofing may be enabled. When enabled and a
fan proof failure is detected, heating and cooling loads will be shut down
until the proof failure goes away or the fan proof alarm is reset or cleared.
The fan may be configured to shut down on a fan proof failure. In this case,
the fan proof alarm must be reset or cleared in order to restart the system.
A dehumidification RH or dewpoint throttling range will determine the range of humidity or dewpoint that represents the full dehumidification load. The dehumidification load can range from 0% (no dehumidification needed) to 100% (full dehumidification needed). Once the dehum load rises above 20%, the controller will activate dehumidification. Once activated, dehumidification will remain active until the dehum load goes back to 0%.
7.6. Dehumidification Control
The DAC dehumidifies by using either mechanical cool stages or a separate
dehumidification device. When dehumidification is needed, the DAC will
generally turn on the dehumidification device or activate stages of cooling up
to a user-defined maximum number of cool stages to be used for
dehumidification.
For units equipped with hot gas reheat, the supply air setpoint reset analog
output will modulate any time the reheat relay is activated, which occurs when
the space temperature drops below the cooling space temperature setpoint.
Additionally, the unit’s primary heating outputs may be used to augment or
replace the hot gas reheat function.
7.6.1. Enabling Dehumidification
The DAC can use several methods to determine if the controlled space requires
dehumidification. If the sensor needed for the method selected is not valid,
dehumidification will not be available until the sensor operation is corrected
or a different method is selected. The methods supported are:
· Dehum by Inside RH
· Dehum by Outside RH
· Dehum by Inside Dewpoint
· Dehum by Outside Dewpoint
7.6.1.1. Dehumidification Setpoint
The active dehumidification setpoint that the controller uses is based on the
occupancy state and the method of determining when dehumidification is
required. Both occupied and unoccupied relative humidity and dewpoint
setpoints are available, depending on the dehumidification method selected.
Figure 7-4 – Dehumidification Graph
7.6.1.2. Dehumidification by Dewpoint
If the selected dehumidification method is by Inside Dewpoint or Outside
Dewpoint, the controller will calculate the dewpoint using the appropriate
temperature and humidity inputs. If either the temperature or humidity input
is not valid, dehumidification will be disabled until the inputs are corrected
or the method is changed.
7.6.1.3. Low Temperature Lockout
To preserve occupant comfort, dehumidification will be disabled if the control
temperature falls below the minimum space during dehumidification setpoint.
Dehumidification will be allowed again when the control temperature rises 2°F
above this setpoint.
7.6.2. Dehumidifying Using Cool Stages
The DAC activates the cooling stages specified for dehumidification based on
the calculated evaporator coil temperature compared to the evaporator coil
temperature setpoint. The evaporator coil temperature is calculated by
converting the suction pressure to a temperature based on the refrigerant
type. For units with a digital or VS compressor, the application will modulate
the compressor to maintain the evaporator coil temperature setpoint and
activate additional fixed capacity compressors as necessary based on the
calculated dehumidification load. In all units, the first
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cooling stage will activate once the load reaches 20%. As the dehumidification
load increases, it will be distributed proportionally across cooling stages
based on the magnitude of the load and the number of available cooling stages.
For example, in a two-stage unit, the first cooling stage will activate at 20%
dehumidification load, and the second cooling stage will activate at 60% load.
Similarly, in a four-stage unit, the first stage will again activate at 20%
load, followed by the second stage at 40%, the third stage at 60%, and the
fourth and final stage at 80%. Thus, the maximum load will be distributed
across all available cooling stages.
The cooling stage will remain active until the load drops to the activation
point for the prior stage or to 0% in the case of the first stage. The
sequence of activation of additional compressors is similar to the staging
during cooling mode, including using the same cooling stage delays and the
cooling PID settings.
7.6.2.1. Digital Scroll Operation During Dehumidification
7.6.2.1.1. Adjusted Minimum Percentage
If additional fixed compressor stages are required to be brought on during
dehumidification, the digital compressor will only be allowed to modulate down
to a minimum of 70%, even if the minimum capacity setpoint for the digital
compressor is set to a lower value. This will reduce the loss of reheat
capacity during low load conditions. If the digital compressor stays at 70%
for the duration of the cool stage-off delay, the fixed compressor will be
turned off.
7.6.2.1.2. Multiple Digital Compressors
If two digital compressors are defined and both are configured to be used for
dehumidification, the second digital compressor will not turn on until the
first digital compressor has reached its maximum capacity, similar to how
digital compressors stage up in cooling mode. Two suction pressure inputs are
supported, so when the second digital compressor is activated, the controller
will use the second suction pressure transducer to calculate the coil
temperature.
7.6.3. Reheat Output
When dehumidification is active, the Reheat output will activate when the
space temperature drops 1°F below the cooling space temperature setpoint.
However, if a return air bypass damper is configured, the Reheat output will
not be permitted to activate until the return air bypass damper reaches 100%.
Once activated, the Reheat output will remain active until the space
temperature either rises above the cooling space temperature setpoint, or
falls below the heating space temperature setpoint (at which point heating
mode will activate).
7.6.3.1. Supply Air Setpoint Reset
When the Reheat output is active, and the Supply Air Setpoint Reset output is
defined, the Reset output will modulate proportionally based on the space
temperature. Specifically, as the space temperature drops from the Cooling
setpoint to the Heating setpoint, the Reset output will increase from 0% to
100%
7.6.4. Primary Heat Used as Reheat
Primary heating stages can be used instead of or in addition to the reheat
output in order to maintain a dehumidification supply air setpoint. When used
in addition to the reheat output, the primary heat will only stage on if the
reheat output has been on for the Heat On-Delay period. Primary heat stages
will then stage on according to the Heat On-Delay time as long as the supply
temperature remains below the dehumidification supply setpoint. The heat
stages will stage off if the supply temperature rises above the
dehumidification supply setpoint plus the dehumidification supply deadband,
according to the Heat Off-Delay setpoint.
7.6.5. Return Air Bypass Damper
The return air bypass (RAB) damper is only used on constant air volume units
and only during dehumidification mode. When defined, the RAB damper acts as
the first form of reheat. The RAB damper modulates from 0-100% as the space
temperature falls below the cooling setpoint. When the space temperature is
equal to the cooling setpoint, the RAB damper will be at 0%. When the space
temperature falls to halfway between the active cooling and heating setpoints,
the RAB damper will be at 100%.
7.6.5.1. Return Air Damper During Dehumidification
If the unit has a separate actuator for the return air (RA) damper (i.e., not
linked to the outdoor air damper), the return air damper will proportionally
close more as the RAB damper opens during dehumidification mode. The rate at
which the RA damper will close is determined by the RA Damper multiplier
setpoint. For example, if the RAB damper
Dehumidification Control
Software Overview · 21
is at 50% and the RA damper multiplier is 10%, the RA damper will close an
additional 5% from its current position.
7.7. Outside Air Control
The outside air damper can be used for several strategies. They are:
· Economization
· Indoor Air Quality (CO2 Control)
· Make-up Air Control
When the outside air damper does not have any functions calling for it to be
open, the modulating damper will move to its minimum position and the two-
position damper will close. During occupancy, the minimum position will be
specified by a user setpoint. During unoccupied, the modulating damper will
fully close to 0%.
7.7.1. Indoor Air Quality
When a CO2 sensor input is present on the DAC or a CO2 value is received from
the E2, the outside air damper may be used to bring fresh air into the
building to reduce CO2 levels. The CO2 sensor’s value is compared to the DAC’s
CO2 setpoint. If the reading exceeds the setpoint:
· The damper will OPEN and remain open until the CO2 value drops below the
setpoint (for twoposition dampers).
· The damper will open and modulate its position based on a PID comparison of
the CO2 sensor reading and the CO2 setpoint (for variable-position dampers).
The damper will open to a user-specified maximum position.
7.7.2. Make-up Air Control
When an exhaust fan input is present on the DAC or an exhaust fan active
signal is received from the E2, the controller will activate make-up air
control. When make-up air is becomes active, the modulating damper will open
to the make-up air minimum damper position setpoint if it is currently less
than that position. If the current modulating damper position is already
greater than or equal to the make-up air minimum position setpoint, no
adjustment to the damper position will occur.
For the two-position damper, when make-up air control is active, the damper
will be set open. When make-up air control is inactive, the damper will close.
7.7.3. Economizer Control
Economizer dampers on rooftop HVAC units are used to bring outside air into
the building for use in cooling. The DAC supports control of two-position
outside air dampers as well as variable-position (analog) dampers.
The DAC controls economization by first determining whether the outside air
conditions are favorable for bringing in outside air (see Section 7.7.3.3.,
Economization Enabling Strategy). If the air is not favorable for
economization, the DAC will close the dampers. If the air is favorable for
economization, the DAC will use the dampers like a preliminary stage of
cooling, opening them first when cooling is first called for, and then
activating more cool stages only if necessary to maintain the setpoint.
7.7.3.1. Operation of Two-Position Dampers During Economization
Two-position dampers are set to the OPEN position when economization is
enabled and the space temperature is above the space economization setpoint.
The damper will remain OPEN until cooling is not required, or until the DAC
determines the outside air is not favorable for economization, at which time
the dampers will be set to the CLOSED position.
7.7.3.2. Operation of Variable-Position Dampers During Economization
When economization is enabled and the space temperature is above the space
economization setpoint, the DAC controls the position of the damper using a
PID algorithm, using a mixed air temperature sensor (mounted where the sensor
may measure the mixture of outside air and return air) and a mixed air temp
setpoint.
The DAC opens and closes the damper incrementally to attempt to maintain the
mixed air temp setpoint. The DAC will close the damper when the mixed air is
below the setpoint to keep cooler air from entering, and open the damper when
the mixed air is above setpoint and requires cooler air from outside.
If the space temperature becomes too cold, or the DAC determines outside air
conditions are not favorable for economization, the DAC will close the damper
to a user-defined minimum damper position.
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7.7.3.3. Economization Enabling Strategy
When communicating with the E2, the DAC only allows economization if it
receives an economizer enable signal from the E2. It does not use other
strategies to enable the economizer. However, in standalone mode, the DAC has
multiple user selectable strategies available for determining whether outside
air conditions are favorable for economization. Each method of economization
checking has a failsafe in case one of the sensors required for the strategy
becomes unavailable.
1. Dewpoint Setpoint When selected, this method requires an outside
temperature and humidity sensor to be connected to the controller. Using these
sensors, an outside dewpoint value is calculated. When the outside dewpoint is
less than the dewpoint setpoint, economization will be enabled. If the outside
humidity sensor fails, the controller will revert to the Dry Bulb Compare
method. If the outside temperature sensor fails, economization will be
disabled.
2. Enthalpy Comparison When selected, this method requires an inside and
outside humidity sensor as well as an outside temperature sensor to be
connected to the controller. Using these sensors, both inside and outside
enthalpy values are calculated. When outside enthalpy is less than inside
enthalpy, economization will be enabled. If the outside humidity sensor fails,
the application will revert to the Dry Bulb Compare method. If an inside
temperature or humidity sensor fails, the application will revert to using the
Enthalpy Setpoint method. If the outside temperature sensor fails,
economization will be disabled.
3. Enthalpy Setpoint When selected, this method requires an outside
humidity and temperature sensor to be connected to the controller. Using these
sensors, an outside enthalpy is calculated. When the outside enthalpy is less
than the enthalpy setpoint, economization will be enabled. If the outside
humidity sensor fails, the application will revert to the Dry Bulb Compare
method. If the outside temperature sensor fails, economization will be
disabled.
4. Dry Bulb Compare When selected, this method requires an outside
temperature sensor to be connected to the controller. When the outside
temperature is less than the inside temperature by at least 2°F,
economization will be enabled. If the outside temperature sensor fails,
economization will be disabled.
5. E2 Zone Enable (BAS) This method is always used when the DAC is
connected to the E2. The controller will read the value of the ECONOMIZATION
output from the E2 zone and enable economization based on that value. The E2
zone must be programmed with its own method of economization checking (refer
to the E2 user manual 026-1610/1614 and on-line help for HVAC Zone application
setup instructions).
7.7.4. Smoke Detection
The DAC may be programmed with a Smoke Detector input, which accepts a dry-
contact digital signal from a smoke alarm or a building control network. When
the smoke detector contact closes to indicate smoke has been detected, the
controller will enter the Emergency Shutdown mode and all of the DAC’s
heating/cooling and fans will be overridden OFF and the outside air damper
will be closed.
7.7.5. Priority When Economization, CO2 Control, and Make-up Air are Used
Together
When Economization, CO2 and Make-up Air control are used together in the same
DAC, it will control a two-position damper using OR logic (OPEN if one or more
strategies require it to be open, CLOSED if none do not require it to be
open).
Variable-position dampers will be controlled based on which control calls for
the highest percentage. In other words, if the damper needs to be set to 60%
to satisfy CO2 fresh air requirements and 40% to satisfy the economization
mixed air temperature setpoint, the damper will be opened to 60%.
7.7.6. Return Damper Control
An optional modulating return air damper may be connected to the DAC. When
connected, the return air damper will modulate inversely proportional to the
outside air damper. For example, if the outside air damper is at 10%, the
return air damper will be at 90%. If the outside air damper goes to 100%, the
return air damper will go to 0%.
During dehumidification, and if a return air bypass damper connected to the
DAC, the return air damper may deviate from its standard calculated position
to
Outside Air Control
Software Overview · 23
assist in the dehumidification process. See Section 7.5.1.1., Variable-Speed
Fan Control in CAV for more details.
7.8. 6.10 Reversing Valve Control
The DAC supports control of a heat or cool reversing valve. The type of
reversing valve can be selected by the user. The valve may be connected to any
relay output on a DAC designated as a reversing valve. If the valve is defined
as a heating reversing valve, the relay will energize when heat is active, and
will deenergize when cool is active. The valve will stay in its current
position when the unit goes to idle mode. Likewise, if the valve is defined as
a cooling reversing valve, the relay will energize only when cool is active,
and will de-energize when heat is active.
7.9. Standalone Functionality
If for some reason a DAC board loses communications with its parent E2 unit
for longer than two minutes, the board will go into Standalone mode.
In Standalone mode, the DAC will continue Temperature Control as normal using
the space temperature and supply temperature as a control inputs. The DAC does
not have an internal schedule and will therefore revert to occupied mode while
operating standalone mode.
Dehumidification and Economization will occur during stand-alone mode only if
the board is equipped with the right local sensors for the strategies
selected.
Any control features that rely on communication with the E2 will not be
available. This includes:
· Demand Shed
· Setpoint Reset
· Optimum Start/Stop
· Summer/Winter Setpoints
· Overrides Initiated by E2
7.10. Control Temperature Sensor Failures
In many cases, the DAC can compensate for sensor failures by substituting
other sensor values. This allows the DAC to continue operating as close to
normal as possible until the failed sensors can be fixed or replaced. However,
it is important to note that if the supply temperature sensor fails, the unit
will not be able to turn on any heating or cooling stages. This sensor must be
repaired immediately.
Control Temp Failure
The preferred sensor to be used to control the space is user configured. By
default, Space Temp 1 is the sensor used. However, Space Temp 2, the average
of both Space Temps, Return Temp, calculated Apparent Temp or a Zone
Temperature from the E2 can be selected as the primary control temperature.
If the preferred sensor fails, a backup sensor will be selected based on a
user configured fallback sensor selection. If this sensor also fails, the DAC
will use the following priority for selecting a control temperature:
1. Space Temp 1
2. Space Temp 2
3. Return Temp
4. Zone Temp (sent from E2)
If no valid control temperature is available, a failure alarm will be
generated and sent to the E2 Alarm Advisory Log.
Outside Air Temp Failure
Failure of the outside air temperature sensor affects Economization only if
the DAC is in standalone mode. In this case, the DAC will disable the
economization strategy until the outside air temperature sensor is repaired.
Mixed Air Temperature Failure
If the DAC has a modulating outdoor air damper defined, it will use the mixed
air temperature sensor as its control input for economization (free-cooling).
If the mixed air temperature sensor fails, it will substitute the supply air
temperature sensor as its control value and continue economization. If neither
the mixed air temperature or supply air temperature
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sensors are available, economization will be locked OFF and the damper will be
closed until the sensor failures can be addressed.
Inside Humidity Failure
The DAC will use the local indoor humidity sensor if it is defined. If no
local indoor humidity sensor is defined, the DAC will use the indoor humidity
value received from the E2. If no valid value is received from the E2, the
dehumidification function will be disabled until a valid indoor humidity
reading is detected. This applies only if the dehumidification strategy is
configured to use inside humidity or inside dewpoint. Also, when in standalone
mode, if no valid inside humidity is detected, the Enthalpy Compare
economization strategy, if selected, will be disabled and the controller will
revert to using the Enthalpy Setpoint method of economization.
Outside Humidity Failure
The DAC will use the local outdoor humidity sensor if it is defined. If no
local outdoor humidity sensor is defined, the DAC will use the outdoor
humidity value received from the E2. If no valid value is received from the
E2, the dehumidification function will be disabled until a valid outdoor
humidity reading is detected. This applies only if the dehumidification
strategy is configured to use outdoor humidity or outdoor dewpoint. Also, when
in standalone mode, if no valid outdoor humidity is detected, the
economization method will revert to Dry Bulb Compare.
7.11. DAC Sensor Calibration Offsets in E2
Figure 7-5 – DAC and E2 Sensor Calibration To verify that sensor readings are
accurate, calibration of sensors may be required. Sensor performance can be
improved by limiting the differences between a sensor’s expected output and
its actual output. Once the sensor differential has been determined, enter the
offset value into the appropriate offset parameter field to calibrate the
sensor. Steps
1. From the E2 Main Menu select
– Configured Applications (Figure 7-6). 2. Select iProDAC from the list – the
iProDAC
Status screen will open (Figure 7-7).
DAC Sensor Calibration Offsets in E2
Figure 7-6 – E2 Configured Applications – Select iProDAC Software Overview · 25
5. Enter the appropriate offset value (Figure 7-9).
Figure 7-7 – iProDAC Status Screen – Press F5
3. Press % SETUP to access the iProDAC Setup screen (Figure 7-8).
4. Press Ctrl + 0 and select F Sensor Offsets or
press to access the C0: MORE tab
and scroll through the tabs to access the Sensor Offsets (Figure 7-9).
Figure 7-9 – Sensor Offset Properties in E2 – C0: MORE Tab
Figure 7-8 – iProDAC Setup Screen in E2 – Ctrl + 0 Tab Menu Sensor Offsets
26 · Discharge Air Controller (DAC) Manual
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8 E2 Setup
8.1. Network Connection to E2
The DAC is capable of communicating with an E2 version 3.0 or above.
Using DAC with a central E2 offers several benefits over simple standalone
control, including:
· Reporting of DAC-related alarms in the Alarm Advisory Log.
· The ability to log DAC inputs in an E2 logging group.
· The ability to share outside air temperature values and control motor room
temperature by sharing input values between the and the E2.
· Remote access to DAC status and programming from the E2 front panel.
· The ability to remotely access the DAC from UltraSite32 or Site Manager, and
to back up, restore, and offline-program DAC configuration along with E2 site
configuration.
Communication between E2 and an DAC takes place over the RS485 MODBUS. Follow
the instructions in Section 3, The MODBUS Network, to connect an DAC to the E2
MODBUS network. Then, follow the instructions in this chapter to set up the
DAC.
E2 PIB COM PORT ASSOCIATIONS
E2 Enclosure (Right Side)
E2 Modem/Expansion COM Card Mounted
COM6
Above PIB
RS232
COM3 Plug-In
Modem Card
RS485
COM1
RS485 COM Card (2 Connectors)
COM4
Serial Device RS232 Port
POWER INTERFACE BOARD (PIB)
COM2
Serial Device RS485 COM Port (2 Connectors)
Figure 8-1 – Location of E2 COM Ports (E2 Versions 3.xx and Below)
Connecting a DAC to an E2 unit requires the E2 to be version 3.0 or above.
Contact Emerson for upgrade information if the controller is a version prior
to 3.0.
An E2 has up to three COM ports that can be assigned for MODBUS communication
(COM2, an RS485 port on the E2 power interface board, and COM4 and COM6, which
are optional ports requiring expansion cards). COM ports can only be used for
one function; in other words, if COM2 is set up as the MODBUS, you cannot
connect MODBUS devices to COM2. Ensure your E2 is equipped with an RS485 COM
Card (P/N 637-4890) and configured in E2 General
Services (, Serial tab) to enable
COM4 or an E2 Expansion COM Card (P/N 637-4871) to enable COM6.
Connect the MODBUS network cable to the threeterminal connector on the COM
port you wish to assign as MODBUS. Like other DAC connections, wire RS485+ to
RS485+, RS485- to RS485-, and the shield cable to the middle terminal. If the
E2 will be the first device in the daisy-chain, set the port’s
Network Connection to E2
E2 Setup · 27
termination jumpers to the TERMINATED & BIASED position (all three jumpers
UP); otherwise, set all jumpers DOWN if not the first device.
8.1.1. Setup Network Ports
Before setting up a DAC, the port on the E2 that has the MODBUS cable
connected must be set up as a MODBUS port.
1. Log in to the E2 with Level 4 access.
2. Press followed by – General
Controller Info.
3. Press + to open the Serial tab of the General
Controller Info setup screens:
8.2. Add and Connect DACs
To enable communications between E2 and the DAC units, the devices must be
added and addressed in E2.
1. Log in to the E2 with Level 4 access.
2. Press – Connected I/O Boards
and Controllers.
Figure 8-2 – Serial Communications Manager Screen
4. This screen will have a “Connection” field for all COM ports on the E2.
Highlight the COM port connection field that will be used for DAC, and press –
LOOK UP. From the list of network types, select MODBUS.
5. Four fields will become visible underneath the COM port connection field,
which pertain to the way the device communicates:
· Baud – Default setting is 19.2k. This must be changed to 9600. (All devices
connected to the same COM port should be set to the same baud rate.)
· Data Size – Leave this field at the default value (8).
· Parity – Leave this field at the default value (None).
· Stop Bits – Leave this field at the default value (1).
Press to save changes and exit.
Figure 8-3 – Connected I/O Screen
3. In the Connected I/O screen, under the ECT tab, Enter the number of DAC
devices in the iProDac number field.
4. Press to return to the Network Setup menu, then select – Network Summary.
5. Locate the DAC units you added to the network list
(press and to scroll through the list). The
default name for a DAC increments up starting with
28 · Discharge Air Controller (DAC) Manual
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iProDAC001.
allows you set the address:.
Figure 8-4 – Network Summary Screen 6. By default, each DAC’s board number in
the network list is indicated by a – (dash). To set the
address and begin communication, press to
Commission. (If you have more than one MODBUS network, specify which network
you want the device to belong to.)
Figure 8-5 – Specify MODBUS Address 7. After choosing the MODBUS network (if
applicable), press Enter and a screen will open that
Figure 8-6 – Set the Address of the DAC
8. When finished, press to return to the Network
Setup menu, then press – Network Summary.
Locate the DACs that you set up, and look at each device’s status in the
Status field. You will see one of the following messages:
· Online – The DAC is communicating normally.
· Offline – The DAC is not communicating, has not been commissioned, is not
functional, or is not powered up. Verify the DAC is powered up, wired
correctly, and has the proper network address, baud rate, and parity.
· Unknown – The DAC is not communicating or has not been commissioned. Verify
if the DAC is powered up, wired correctly, and has the proper network address,
baud rate, and parity.
· No Port – No port is set up in the E2 Serial Configuration Manager to be a
MODBUS port.
· Wrong FW Rev – This message is likely caused by the DAC having a firmware
version older than the minimum revision required by E2 for communication.
Replace the DAC with a new controller that has the latest version of firmware
on
Add and Connect DACs
E2 Setup · 29
it.
Figure 8-7 – Network Summary Screen
8.3. Viewing the DAC Status Screen
Once you have added an DAC to the E2, you will be able to see the status of
the DAC board(s) from the front panel.
1. From the Main Status Screen, press key and select – Configured
Applications.
2. Select DAC from the menu. If multiple DACs are associated with this E2,
the DAC Summary Screen will be shown. To see a single DAC status screen, use
the arrow keys to highlight the DAC you wish
to view, and press .
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Connections
9.1. The DAC Connector Descriptions
Connector
Function
Connector for 24VAC/DC power supply analog inputs (Pb1 – Pb10, PbC) Additional
power (+5VDC, +12VDC, GND)
Opto-insulated analog outputs (Out1 – Out6, GND) 24VAC/DC power supply for the
opto-insulated analog output
Volt-free opto-insulated digital inputs (DI1 – DI20, IDC)
USB port for downloads (BIOS, ISaGRAF® application, maps of parameters, remote
display applications, network configuration, website) and uploads (log files)
TCP/IP Ethernet port
Connector
Function
RS485 Master connector Rx and Tx LED to indicate that communication is active
Closed circuit terminal (Term)
Digital relay outputs (for digital outputs with volt-free contacts) 3 NO
relays, 1 common
Digital relay outputs (for digital outputs with live contacts) 3 NO relays, 1
common and 2 volt-free (Neutral)
Digital relay outputs (for digital outputs with volt-free contacts) 5 NO
relays, 1 common
Digital relay outputs (for digital outputs with live contacts) 5 NO relays, 1
common and 2 volt-free (Neutral)
Digital relay outputs 2 NO relays, 1 common
Digital relay outputs (only for 215D versions) 5 NO relays, 1 common and 1
volt-free (Neutral)
Table 9-1 – Descriptions of the Connections
Connector for remote terminal (VISOGRAPH), maximum 2 terminals per DAC.
CANBUS connector for expansions (IPEXx0D) and drivers for electronic valves
(XEVx0D) Rx and Tx LED to indicate that communication is active Closed circuit
terminal (Term)
RS485 Slave connector Rx and Tx LED to indicate that communication is active
Closed circuit terminal (Term)
Table 9-1 – Descriptions of the Connections
The DAC Connector Descriptions
Connections · 31
9.2. Terminal Number Descriptions
Terminal No.
Type of Input
Description
1
Supply
Power 24VAC or 24VDC(-)
2
Pb1
Analog Input 1 (Temperature, 0-10V, 0-1V, 0-5V)
3
Pb2
Analog Input 2 (Temperature, 0-10V, 0-1V, 0-5V)
4
Pb3
Analog Input 3 (Temperature, 0-10V, 0-1V, 0-5V)
5
Pb4
Analog Input 4 (Temperature, 0-10V, 0-1V, 0-5V)
6
Pb5
Analog Input 5 (Temperature, 0-10V, 0-1V, 0-5V)
7
PbC
Common for temperature inputs (DO NOT TIE TO GROUND)
8
GND(-)
Additional power reference 5VDC and 12VDC and analog inputs (0 -10V,
0 -1V, 0 -5V)
9
Supply
Power 24VAC or 24VDC(+)
10
Pb6
Analog Input 6 (Temperature, 0-10V, 0-1V, 0-5V)
11
Pb7
Analog Input 7 (Temperature, 0-10V, 0-1V, 0-5V)
12
Pb8
Analog Input 8 (Temperature, 0-10V, 0-1V, 0-5V)
13
Pb9
Analog Input 9 (Temperature, 0-10V, 0-1V, 0-5V)
14
Pb10
Analog Input 10 (Temperature, 0-10V, 0-1V, 0-5V)
15
+5V
Additional power +5VDC
16
+12V
Additional power +12VDC
21
Out1
Opto-insulated analog output 1, 0-10V
22
Out2
Opto-insulated analog output 2, 0-10V
23
Out3
Opto-insulated analog output 3, 0-10V
24
Out4
Opto-insulated analog output 4, 0-10V
25
GND(-)
Common opto-insulated analog output
26
Out5
analog output 5, 0-10V
27
Out6
analog output 6, 0-10V
28
Supply
Power for opto-insulated analog outputs at 24VAC or 24VDC(-)
29
Supply
Power for opto-insulated analog outputs at 24VAC or 24VDC(+)
30
GND(-)
Common opto-insulated analog output
40
DI1
Opto-insulated digital input 1
41
DI2
Opto-insulated digital input 2
42
DI3
Opto-insulated digital input 3
43
DI4
Opto-insulated digital input 4
44
DI5
Opto-insulated digital input 5
45
DI6
Opto-insulated digital input 6
46
DI7
Opto-insulated digital input 7
47
DI8
Opto-insulated digital input 8
Table 9-2 – Terminal Number Descriptions
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Terminal No.
Type of Input
Description
48
DI9
Opto-insulated digital input 9
49
DI10
Opto-insulated digital input 10
50
GND(-)
Common opto-insulated digital inputs 1 to 20 (inputs 24VAC or 24VDC)
(unsupported)
51
DI11
Opto-insulated digital input 11 (unsupported)
52
DI12
Opto-insulated digital input 12 (unsupported)
53
DI13
Opto-insulated digital input 13 (unsupported)
54
DI14
Opto-insulated digital input 14 (unsupported)
55
DI15
Opto-insulated digital input 15 (unsupported)
56
DI16
Opto-insulated digital input 16 (unsupported)
57
DI17
Opto-insulated digital input 17 (unsupported)
58
DI18
Opto-insulated digital input 18 (unsupported)
59
DI19
Opto-insulated digital input 19 (unsupported)
60
DI20
Opto-insulated digital input 20 (unsupported)
61
IDC
Common opto-insulated digital inputs 1 to 20 (volt-free, dry contact)
70
RL1
Relay 1 normally open contact
71
C
Common relays 1, 2, and 3
72
RL2
Relay 2 normally open contact
73
RL3
Relay 3 normally open contact
74
C
Not Used
75
C
Not Used
76
RL4
Relay 4 normally open contact
77
RL5
Relay 5 normally closed contact
78
RL6
Relay 6 normally closed contact
79
RL7
Relay 7 normally closed contact
80
C
Common relays 4, 5, 6, 7, and 8
81
RL8
Relay 8 normally closed contact
82
C
Not Used
83
C
Not Used
84
RL9
Relay 9 normally closed contact
85
RL10
Relay 10 normally closed contact
86
C
Common relays 9 and 10
87
RL11
Relay 11 normally closed contact
88
RL12
Relay 12 normally closed contact
89
RL13
Relay 13 normally closed contact
90
C
Common relays 11, 12, 13, 14, and 15
91
RL14
Relay 14 normally closed contact
Table 9-2 – Terminal Number Descriptions
Terminal Number Descriptions
Connections · 33
Terminal No.
Type of Input
Description
92
RL15
Relay 15 normally closed contact
93
C
Not Used
94
RS485 Master
RS485 Master connection (-)
95
RS485 Master
RS485 Master connection (+)
96
RS485 Master
RS485 Master connection (insulated gnd)
97
RS485 Slave
RS485 Slave connection (-)
98
RS485 Slave
RS485 Slave connection (+)
99
RS485 Slave
RS485 Slave connection (insulated gnd)
100
CAN Bus
CAN Bus connection (+), not open
101
CAN Bus
CAN Bus connection (-), not open
102
CAN Bus
CAN Bus connection (insulated gnd), not open
103
Remote Display Connection for VISOGRAPH remote terminal (Vnr)
104
Remote Display Connection for VISOGRAPH remote terminal (+)
105
Remote Display Connection for VISOGRAPH remote terminal (-)
106
Modem Reset
Not Used
107
Modem Reset
Not Used
Table 9-2 – Terminal Number Descriptions
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9.3. Technical Specifications
9.3.1. Analog Inputs
Analog conversion 10-bit A/D converter type:
Number of inputs: 10
Type of analog input: (configurable via software parameter)
NTC Dixell (-50T110°C; 10K±1% at 25°C) PTC Dixell (-55T115°C; 990±1% at 25°C) Digital input (volt-free contact) Voltage: 0 – V, 0 – 5V, 0 – 10V (input resistance 3.7K) Current: 0 – 20mA, 4 – 20mA (input resistance 100)
Digital input status 250ms variation detection time:
Accuracy:
NTC, PTC: ±1? 0-1V: ±20mV 0-5V: ±100mV 0-10V:±200mV 2-20mA, 4-20mA: ±0.30mA
Additional power: +12V: 200mA in total +5V: 100mA
Table 9-3 – Analog Input Specifications
9.3.2. Digital Inputs
Type: (configurable via software parameter)
Opto-insulated volt-free External power 24VAC/DC ±20%
Number of inputs: 20
Digital input status 250ms variation detection time:
Table 9-4 – Digital Input Specifications
CAUTION! If the digital inputs are used with voltage, use another transformer (do not use the same secondary of the controller’s power) in order to prevent the inputs from malfunctioning or being damaged.
CAUTION! Any inputs that are powered with a voltage that differs from that supplied by the device (+12V or +5V) must be powered separately with another transformer (do not use the same secondary of the controller’s power) in order to prevent the inputs from malfunctioning or being damaged.
Technical Specifications
Connections · 35
9.3.3. Analog Outputs
Type:
Number of outputs: Type of analog output: (configurable via software
parameter) Maximum load:
Accuracy:
Resolution:
Opto-insulated with separate 24VAC/DC power supply
10
4 fixed outputs 0-10VDC (Out1 – Out4) 2 configurable outputs 0-10VDC, 4-20mA
(Out5 and Out6)
40mA (Out1 – Out4) 20mA (Out5 and Out6) max with configured outputs 0-10VDC
400 max with configured outputs 4-20Ma 22 per live analog output
Out1 – Out4: ±2% full scale Out5 Out6: ±2% full scale
8bit
Table 9-5 – Analog Outputs Specification
9.3.4. Digital Outputs
Type:
Relays with NO contacts
Number of outputs:
10 or 15, depending on the model
Type of output: (configurable via software parameter)
Relays with normally open contact
Maximum load: 5A(250VAC) SPST 5(2)A
Table 9-6 – Digital Outputs Specifications
CAUTION! Verify the capacity of the output used. There is double insulation between the digital outputs and the low voltage of the rest of the circuit. Do not use different voltages for the various groups of relays nor within each group.
CAUTION! The electrical devices controlled by these analog outputs must be powered separately with another transformer (do not use the same secondary of the controller’s power) in order to prevent the outputs from malfunctioning or being damaged.
36 · Discharge Air Controller (DAC) Manual
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9.4. Wiring
Figure 9-1 – DAC Detail NOTE: DI11 through DI20 (pins 51-60) are not available
for use in the DAC controller.
Wiring
Connections · 37
10 Using the Visograph
10.1. Viewing Status
For visograph button functionality, see Section 3.1.2.2., Visograph Navigation
section.
10.1.1.Input Status
1. From the main menu, select 1 to navigate to the status screens
2. The status of the most common DAC inputs are shown on this screen
3. All temperature units are in °F. Suction pressures are shown in PSI.
Figure 10-2 – Status – Outputs
10.1.3.VAV Fan Status
When the application is set to VAV, this screen will allow you to monitor the
duct static pressure as controlled by the fan or relief damper:
Figure 10-1 – Status – Inputs
10.1.2.Output Status
Press the RIGHT arrow to navigate to the output status screen. The status of
the most common DAC outputs are shown on this screen:
· Operation mode of controller · Heating/Cooling stages · Fan/Outdoor Damper
Figure 10-3 – Status – VAV Fan
10.2. Viewing I/O Configuration
10.2.1.Analog Inputs
From the main menu, select 3 to navigate to the I/O Config screens. The
current configurations of the local analog inputs are shown on this screen.
These values may be edited using the visograph; however, if the DAC is
communicating with E2, the E2 will override any changes made.
38 · Discharge Air Controller (DAC) Manual
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Figure 10-4 – I/O Config – Analog Inputs
10.2.2.Relay Outputs
1. Press the RIGHT arrow to navigate to the relay outputs configuration
screen.
The current configuration of local relay outputs 1-10 are shown on this
screen.
2. Press the RIGHT arrow to navigate to the next screen showing outputs
11-15.
Figure 10-6 – I/O Config – Analog Outputs
10.2.4.Digital Inputs
Press the RIGHT arrow to navigate to the digital inputs configuration screen.
The configuration of all supported digital inputs are shown on this screen.
All digital inputs are fixed in position and cannot be edited.
Figure 10-7 – I/O Config – Digital Inputs
10.3. Relay Output Overrides with Visograph
Figure 10-5 – I/O Config – Relay Outputs 1-10 and 11-15
10.2.3.Analog Outputs
Press the RIGHT arrow to navigate to the analog outputs configuration screen.
The current configuration of all local analog outputs are shown on this
screen:
1. Press 6 on the main menu to navigate to the output override screens
The first override page shows all of the relay outputs. To override a relay:
2. Use the UP and DOWN arrows to navigate to the desired relay output.
3. Press the ENTER key. The field will start blinking.
Relay Output Overrides with Visograph
Using the Visograph · 39
4. Use the UP and DOWN arrows (T4 and T5), to change the override state to
the desired value. The choices are Auto, ON, and OFF.
5. Press ENTER to activate the new override state.
6. Press MENU to go back to main menu screen.
Figure 10-9 – Overrides – Analog Outputs
Figure 10-8 – Overrides – Relay Outputs
NOTES: Relay output overrides initiated with the visograph will automatically
time out after one hour. The E2 interface may be used to activate fixed or
timed overrides. The fixed overrides from E2 will not time out after one hour.
The DAC will cancel any active E2 initiated overrides if it loses
communication with the E2. To navigate to the Analog Output override screen on
the next page, press the RIGHT arrow (T8).
10.3.1.Analog Output Overrides with Visograph
From the main menu, press 6 to navigate to the output override screens. Then
press the RIGHT arrow (next page) to move to the analog output override
screen:
10.3.1.1. To Override an Analog Output
1. Use the UP and DOWN arrows to navigate to the desired analog output.
2. Press the ENTER key. The field will start blinking.
3. Use the UP and DOWN arrows (T4 and T5), to change the override to the
desired voltage. The choices are Auto, ON, and OFF.
4. Press ENTER to activate the new override state.
5. Press MENU to go back to main menu screen.
10.3.1.2. To Clear an Analog Output Override
Change the override value back to 10.1 V
The value 10.1 signifies that the output is not overridden but is under normal
control of the application.
NOTES: Analog output overrides initiated with the visograph will automatically
time out after one hour. The E2 interface may be used to activate fixed or
timed overrides. The fixed overrides from E2 will not time out after one hour.
The DAC will cancel any active E2 initiated overrides if it loses
communication with the E2.
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Index
A Addressing iPro DAC 5 Analog Inputs 6 Analog Outputs 10 Application Mode 15
AWG 3
C CAV 15 CAV Mode 15 Connecting iPro DACs 28 Connections 31 Connector
Functions 31 Cooling Mode 16
D Daisy Chain Configuration 4 Dehumidification Control 20 Dehumidifying Using
Cool Stages 20 Digital Inputs 8 Digital Loads 10 Digital Outputs 10 Digital
Scroll 21 DIN Mounting 2 Distance of Wiring 3
E E2 27
Add and Connect iPro DAC 28 Addressing 28 Setup Network Ports 28 E2 and the
DAC 27 E2 Network Connection 27 E2 Setup 27 Economizer Control 22
F Fan Control 18
H Heating Mode 17
I I/O Points 1 Independent Control 1 Indoor Air Quality 22 Input and Output
Setup 6 Input Specs 35 Inputs 6 Installation 2
L LEDs 14
M MODBUS 4
Termination 6 Wiring 4 MODBUS 485 4 MODBUS Addressing for iPro DAC 5 MODBUS
Network 4 Modes 15 Mounting and Powering 2
O Operational Modes 15 Output Specs 36 Outputs 10 Outside Air Control 22
P Powering the iPro DAC 2
R Reheat Output 21 Relay Outputs 10 Return Damper Control 23 Reversing Valve
Control 24 RS485 4
S Sensor Failures 24 Smoke Detection 23 Software Overview 15 Space Temperature
Control 16 Specifications 35
analog inputs 35 analog outputs 36
Index · 43
digital inputs 35 Standalone Mode 24 Status Screen
DAC 30 Supply Air Setpoint Reset 21 Supply Temperature Control 16
T Terminal Load Calculation 16 Terminal Number Descriptions 32 Termination 6
MODBUS 6 Transformers and Ratings 3
V VAV 15 VAV Mode 15 Visograph 38
Analog Output Overrides 39, 40 Buttons 5 Clear Analog Output Override 40
Connectivity 5 Override Analog Output 40 Relay Output Overrides 39 VAV Fan
Status 38 Viewing I/O Configuration 38
analog inputs 38 analog outputs 39 digital inputs 39 relay outputs 39 Viewing
Status 38 input status 38 output status 38 Visograph Connectivity 5
W Warnings
Analog Inputs 8 Analog Outputs 11 Output Capacity 36 Transformers 36 Voltages
36 Wire Length 3 Wire Distance 3 Wire Gauge/Types 3 Wiring 13, 37
44 · Discharge Air Controller (DAC) Manual
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For Technical Support call 833-409-7505
or email ColdChain.TechnicalServices@Emerson.com
The contents of this publication are presented for informational purposes only
and they are not to be construed as warranties or guarantees, express or
implied, regarding the products or services described herein or their use or
applicability. Emerson reserves the right to modify the designs or
specifications of such products at any time without notice. Responsibility for
proper selection, use and maintenance of any product remains solely with the
purchaser and end-user. ©2021 Emerson is a trademark of Emerson Electric Co.
References
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