LENNOX 0624-L5 IMC BACnet Module User Manual

Corp. 0624−L5
02/2008 (Supersedes 08/06)
IMC BACnet®
Module

General

The IMC BACnet® module allows communication between the Lennox IMC (M1−7, v5.02+) controller and a BACnet MSTP network. The module translates input and output variables between the Lennox SysBus protocol and the BACnet protocol.
The BACnet® module has been developed to communi- cate with building automation systems that support the BACnet Application Specific Controller (B−ASC) device profile.
A Lennox zone sensor, a BACnet® network zone sensor, or a BACnet thermostat may be used to send the zone temperature or thermostat demands to the IMC.

Table 1. IMC BACnet® Hardware Specifications

Electrical

Power Supply| 24VAC 50/60Hz (18−30VAC)
Power Consumption| < =7 watts
Connector| Two position terminal block (Polarity Sensitive) (Hot, Com)
Environment
Operating Temperature Range| −40F to 155F
Storage temperature Range| −40F to 185F
RH| 10−95% RH non−condensing
Field Connections
BACNET MSTP|
Transceiver| RS−485
Connector| Three position terminal block (+ _ G)
Baud Rate| 38.4K
Cable Type| Twisted pair w/shield, 22AWG min. Belden type 88761 or 8761. Lennox 27M19, 94L63 or 68M25
Max. Cable Length| 4000 ft Repeater is required for longer lengths.
Bus Termination| 120 ohms on last module in chain.
LENNOX SysBus| RS485
Connector| Two position terminal block
Baud Rate| 9600
Cable Type| Twisted pair w/shield, 22AWG min. Belden type 88761 or 8761. Lennox 27M19, 94L63 or 68M25.
Max. Cable Length| 4000 ft. Repeater is required for longer lengths
Bus Termination| None
Physical
Dimensions| 3.1 x 3.5 x 1.25 in. (WxDxH)
Weight| 0.1 lbs (0.04Kg)
PCB Material| FR4 Conformal coated
Mounting| Four brass 5 in. standoffs for #6 screws.

Network Limitations

The Lennox BACnet module does not support the COV (change of value) service.
Lennox supports up to 31 unique MAC addresses utilizing the IMC address DIP switches. Specific performance with the controls being used is the responsibility of the controls integrator and/or the controls manufacturer.
While there are 31 unique MAC addresses allowed, they must be in the range of 1−31.
All modules have the same device name Lennox”. The device name cannot be made unique.

Network Cable

Module is compatible with MSTP® EIA−485 daisy−chain networks communicating at 38.4 kbps. Connect the BACnet MSTP network cable to the IMC BACnet module. The module operates at a 38.4K baud rate. It is compatible with  twisted pair, shielded 22AWG minimum cable such as Belden 8761, 88761 and Lennox The IMC BACnet catalog numbers 27M19, 94L63 or 68M25. A maximum of 31 IMC BACnet modules can be included per network.
The network cable should be routed using best practices to avoid induced noise. Do not route alongside power lines, or in proximity to high voltage or high frequency devices, such as ignition controls and variable frequency drives.
The BACnet MSTP maximum total bus length (without repeater) of 4000ft. (1219m) applies to this device.
Daisychain each module to the network and connect the network cable shield to the earth ground at the control panel, and at the G terminal of each BACnet module in the chain.

Network Bus Termination
A 120 ohm 1/4 watt resistor (provided in field kit) must be added between the

• and − terminals on the BACnet connection on the last module in the daisy chain.

IMPORTANT
Install the resistor on the LAST module only. Do not add a resistor to each module.
IMPORTANT
A qualified systems integrator with adequate training and experience is required to integrate and commission the IMC BACnet Module into a third party BACnet building automation system. A BACnet configuration software tool is required to commission the BACnet network.

Configuring the IMC Unit Controller

ECTO Settings
Use the IMC pushbutton and DIP switches to manually adjust the following control parameters (see IMC manual).
PC can also be used with Unit Controller software and a PC converter.
Lennox Zone Sensor Installed:

1. Set ECTO 6.01 to option 3 (zone sensor system mode with return air sensor back−up).
2. Set ECTO 6.17 to option 1 (continuous blower during occupied).
3. Set ECTO 6.02−6.05 as specified (back−up occupied and unoccupied heating and cooling setpoints). ® BACnet

Zone Sensor Installed:

1. Set ECTO 6.01 to option 3 (zone sensor system mode with return air temperature back−up).
2. Set ECTO 6.17 to option 1 (continuous blower during occupied).
3.  Set ECTO 5.27 to option 2 (network zone sensor option).

BACnet Thermostat Installed:
Set ECTO 6.01 to option 6 (remote demand system mode with return air sensor back−up).
IMC Settings

1. Be sure the occupied 24 VAC input is energized by adding a jumper wire between TB1−8 and 9. In the event that communication is lost between the IMC BACnet module and the IMC, the IMC will operate in the occupied mode and  use the occupied backup setpoints.
2. Set the BACnet device I.D. (and MAC address) with the unit address DIP switch on the IMC main board (M1−7). See figure 2. Each IMC on the BACnet network must have a different address between 1 and 31. Do not use 0 for  addressing.

The value of the five switches on the address DIP switch are labeled on the printed circuit board (1, 2, 4, 8, or 16). Add the values of the five switches set to the ON position. See figure 3.

IMC Version
This module requires a rooftop unit IMC M1−7 version 5.02 or higher. An IMC upgrade kit is available for older M1−7 versions. M1−6 and earlier IMCs cannot be used with the BACnet module; contact Lennox Technical Support at 800−453−6669. Check IMC version as follows:

1. Locate IMC board in compressor area. Refer to IMC manual provided with rooftop unit.
2. Set the MODE DIP UNIT TEST” and RECALL” switches to ON”. See figure 4.
3. The IMC LEDs will display the current IMC version.
4. Be certain to return the UNIT TEST” and RECALL” switches to OFF” after viewing the version number.
   Communication to the IMC is interrupted while these MODE DIP switches are ON”.

IMC Version
This module requires a rooftop unit IMC M1−7 version 5.02 or higher. An IMC upgrade kit is available for older M1−7 versions. M1−6 and earlier IMCs cannot be used with the BACnet module; contact Lennox Technical Support at 800−453−6669. Check IMC version as follows:

1. Locate IMC board in compressor area. Refer to IMC manual provided with rooftop unit.0
2. Set the MODE DIP UNIT TEST” and RECALL” switches to ON”. See figure 4.
3. The IMC LEDs will display the current IMC version.
4. Be certain to return the UNIT TEST” and RECALL” switches to OFF” after viewing the version number. Communication to the IMC is interrupted while these MODE DIP switches are ON”.

Data Update Rate
If the following BACnet® variables are not updated for a period of 5 minutes, the IMC will go into the back up modes described in the BACnet Connection Failure Section.
Application Mode Control AO:101 (when ECTO 6.01=4−7) Space Temperature Input AO:113 (when ECTO 5.27=2)
Whenever either of these ECTO selections are made, it is highly recommended the IMC get updated in less than 2 minutes.

Start Up Unit Operation − Before BACnet Network is Commissioned
Lennox Zone Sensor Installed: Prior to commissioning, no BACnet setpoint is available. The unit will be off. Two minutes after power−up (ECTO 5.25), the IMC will operate the unit based on the IMC ECTO unoccupied backup setpoints (heating = 60°F, cooling = 85°F) and current zone temperature read by the Lennox zone sensor. BACnet Zone Sensor Installed: Prior to commissioning, neither BACnet setpoint nor sensor data are available. The unit will be off. Five minutes after power−up, the IMC will operate the unit based on the IMC ECTO unoccupied backup setpoints (heating = 60°F, cooling = 85°F) and the current zone temperature read by an additional Lennox zone sensor if installed. If the Lennox zone sensor is not installed, the IMC return air temperature sensor is used as backup (ECTO 6.01). BACnet Thermostat Installed: Prior to commissioning, no BACnet thermostat command is available. The unit will be off. Five minutes after power−up, if no application mode command has been received, the IMC will operate the unit based on the IMC ECTO unoccupied backup setpoints (heating = 60°F, cooling = 85°F) and the current zone temperature read by the Lennox zone sensor or the IMC return air temperature sensor depending on the choice of backup (ECTO 6.01).

Normal Unit Operation − After BACnet Network

Is Commissioned The occupancy of the space can be determined using any combination of the following control points:

• BACnet Network scheduling
• Manual override
• Space occupancy sensor

Lennox Zone Sensor Installed:

The unit is off for up to two minutes after power−up (ECTO 5.25) unless the BACnet Network sends a setpoint. The unit will operate based on this setpoint and the temperature from the Lennox zone sensor. In addition to control points, space occupancy can be manually overridden using a Lennox zone sensor equipped with an optional after hours switch.
BACnet Zone Sensor Installed:
The unit is off for up to five minutes after power−up unless the BACnet Network sends a setpoint and BACnet zone sensor data. The unit will operate based on this setpoint and temperature data.
BACnet Thermostat Installed:
The unit remains off for up to five minutes after power−up unless the BACnet Network sends a thermostat command. The unit will operate based on the most recently received thermostat command.

Communication Check
Use the following table as a guide once the IMC and BACnet Module are connected and powered. See figure 3.
Table 2. IMC to BACnet® Module Communication

LED

|

Action

---|---
IMC BUS and XMIT LEDs flash.| None. Indicates normal communication.
IMC BUS and XMIT LEDs are off.| 1−
2−
3−| Check cable connection between the IMC module.
Reverse polarity of the cable between the IMC and BACnet Module. Check 24VAC power to BACnet module.
 | 1−| Make sure unit addresses are between 1 and 31.
IMC BUS LED flashes but XMIT LED is off.| 2−| Make sure MODE DIP RECALL switch is OFF.
 | 3−| Make sure MODE DIP ECTO switch is OFF.
 | 4−| Make sure MODE DIP UNIT TEST switch is OFF.

Table 3. BACnet Network Communication
Use the following table as a guide once the BACnet network is set up and operating.

LED

|

Action

---|---
BACnet communication transmit and receive LEDs flash.| None. Indicates normal communication.
BACnet communication LEDs are off.| 1−Check BACnet network connections.
2−Make sure BACnet network is commissioned.
3−Make sure 24 volts is connected to the BACnet module.
4−Make sure unit address is between 1 and 31.

Connection Failure
Table 4. Connection Failure
Control following a connection failure depends on where the failure occurs, and which input device has been used.

| Between IMC and BACnet Module|

BACnet Network

---|---|---
 | 1−| During the 5 minutes following a failure, the IMC cycles on last set-| 1−| IMC cycles on last setpoint.

Lennox Zone Sensor

|

2−

3 −

| point.

IMC resets. No heating or cooling during 2 minutes (ECTO 5.25) following reset.

IMC cycles based on ECTO backup setpoints.

| 2−| Last occupancy input is used.
 | 4−| Occupancy is determined by hardware input at TB1.|  |
 | 1−| During 5 minutes following failure, IMC continues current opera-| 1−| During 5 minutes following failure, IMC con-
 |  | tion: heat, cool, or off.|  | tinues current operation: heat, cool, or off.
BACnet Zone Sensor| 2−

3−

4−

| IMC resets. No heating or cooling during 5 minutes following reset. IMC uses ECTO backup setpoints.

IMC attempts to use Lennox zone sensor as backup. If this fails,

| 2−

3−

| IMC uses ECTO backup setpoints.

IMC attempts to use Lennox zone sensor as backup. If this fails, IMC uses return−air−sen-

 |  | IMC uses return air sensor backup.|  | sor backup.
 | 5−| Occupancy is determined by hardware input at TB1.| 4−| Last occupancy input is used.
 | 1−| During 5 minutes following failure, IMC continues current opera-| 1−| During 5 minutes following failure, IMC con-
 |  | tion: heat, cool, or off.|  | tinues current operation: heat, cool, or off.
BACnet

Thermos tat

| 2−

3−

4−

| IMC resets. No heating or cooling during 5 minutes following reset. IMC uses ECTO backup setpoints.

IMC uses return−air−sensor backup.

| 2−

3−

4−

| IMC uses ECTO backup setpoints. IMC uses return−air−sensor backup. Last occupancy input is used.
 | 5−| Occupancy is determined by hardware input at TB1.|  |

BACnet® Data Points
By convention input and output are described from the point of view of a client device communicating with the interface module.
Outputs are values written to the interface

BACnet Object Name

| Table 5. Inputs To IMC
Object Type: ID: Units                             Description
---|---
Application Mode Control| AO: 101:95 (No_ Units)| Unit application
0| −Auto|  | Heating or cooling. Default after reset.
1| −Heat| Heating only.
3| −Cool| Cooling only.
6| −Off| Unit off.
9| −Fan only| No heating or cooling allowed.
208| −Fan auto| Main fan (blower) auto. Default after reset.
209| −Fan on| Main fan (blower) on.
216| −Exhaust auto| Power exhaust fan auto. Default after reset.
217| −Exhaust on| Power exhaust fan on.
218| −Exhaust off| Power exhaust fan off.
224| −Idle| Heat / cool off. Default after reset.
225| −Heat1| Heat 1
226 −Heat2 (heat pump only)| Heat 2. Heat pump emergency heat.
227| −Heat3| Heat 3. Full heating.
228| −Cool1| Cool 1
229| −Reheat lo| Supermarket reheat (lo)
230| −Reheat high| Supermarket reheat (hi)
232| −Cool2| Cool 2
236| −Cool3| Cool 3. Full cooling.
254| −Reset| Force controller reset
255| −Null| Same as auto.
Outdoor Air Min Pos Control| AO: 102 : 98 (Percent)| Min economizer damper position
Occupancy Override Control| AO: 103: 95 (No_Units)| Zone occupied status
Occupancy Scheduler Control| AO: 104: 95 (No_Units)| Occupancy scheduler input used to put controller unit into different occupancy modes.
Occupancy Sensor Input| AO: 107: 95 (No_Units)| Occupancy sensor input. Used to indicate the presence of occu- pants
Space Dehumidification Setpt| AO: 108: 98 (Percent)| Zone relative humidity set point
Temperature Setpoint (abs)| AO: 109: 64 (Deg. F)| Zone temperature setpoint
Temperature Setpoint Offset| AO: 110: 64 (Deg. F)| Zone temp setpoint offset
Space Temperature Input| AO: 113: 64 (Deg. F)| Remote zone temp.
Emergency Override Control| AO: 114: 95 (No_Units)| Emergency smoke override
Compressor Enable Control| AO: 115: 98 (Percent)| Compressor enable
Primary Heat Enable Control| AO: 117: 98 (Percent)| Primary heat enable
Auxiliary Heat Enable Control| AO: 119: 98 (Percent)| Auxiliary heat enable
Duct Static Setpoint| AO: 123: 58 (Inches−of−water)| Duct static pressure setpoint
Building Static Setpoint| AO: 124: 58 (Inches−of−water)| Building static pressure setpoint
Discharge Air Cooling Setpoint| AO: 125: 64 (Deg. F)| Discharge air cooling setpoint
Discharge Air Heating Setpoint| AO: 126: 64 (Deg. F)| Discharge air heating setpoint
Supply Fan Capacity Input| AO: 127: 98 (Percent)| Supply fan capacity setting
Exhaust Fan Capacity Input| AO: 128: 98 (Percent)| Exhaust fan capacity setting
IMC Version [00]….. [07]| AI: 200−207 : 95 (No_Units)| IMC firmware version. (null terminated ASCII)
---|---|---
Unit ID| AI: 231 : 95 (No_Units)| Unit ID $3x−Gas/Elect.

$4x−Elect/Elect.

$5x−Heat Pump

Unit Status| AI :232 : 95 (No_Units)|

Unit operation mode (i.e. cool, heat, etc.)

1 − HVAC heat|
2 − HVAC morning warm−up|
3 − HVAC cool|
5 − HVAC pre−cool|
6 − HVAC off|
7 − HVAC test|
8 − HVAC emergency heat|
9 − HVAC fan only|
12 − HVAC max heat|
14 − HVAC dehumidification|
129 − HVAC fresh air heating|
131 − HVAC fresh air cooling|
145 − HVAC defrost 1|
161 − HVAC defrost 2|
177 − HVAC defrost 1, 2|
Space Temperature| AI: 239 : 64 (Deg. F)|
Discharge Air Temperature| AI: 240 : 64 (Deg. F)| Supply air temperature
Effective Occupancy| AI: 241 : 95 (No_ Unit)| Zone occupied status
Local Outside Air Temperature| AI: 242 : 64 (Deg. F)| Outdoor air temperature
Local Space Temperature| AI: 243 : 64 (Deg. F)| Zone Temperature, local
Outside Air Damper| AI: 244 : 98 (Percent)| Economizer damper position
Heat Primary| AI: 245 : 98 (Percent)| Primary heating status
Heat Secondary| AI: 246 : 98 (Percent)| Heat pump electric strip heating status
Cool Primary| AI: 247 : 98 (Percent)| Cooling compressor 1−4 status (on/off)
Economizer Enabled| AI: 248 : 95 (Percent)| Economizer outdoor air suitable
Supply Fan Status| AI: 250 : 98 (Percent)| Supply fan status
Space Temperature Set Point (Eff)| AI: 252 : 64 (Deg. F)| Zone temperature set points
Current Error| AI: 253 : 95 (No_Units)| Currently displayed error code
Error Pointer| AI: 254 : 95 (No_Units)| Error pointer. This value points to the next available alarm code location. It runs from 0 to 83 and then rolls−over to 0. Tracking this value and using the ten most recent error codes (below) allows an application to determine when new errors are logged by the IMC, what those errors are, and if any errors have been missed due to network delays or for any other reason.
Most recent Error 1..10| AI: 255−264 : 95 (No _Units)| IMC alarm codes as listed in the IMC manual.
Space CO2 Sensor (Local)| AI : 274 :96 (Parts per million)| Zone CO2 level (PPM), local
Space Humidity (Local)| AI: 276 : 98 (Percent)| Zone relative humidity, local
Dehumidification Set Point (Eff)| AI: 278 : 98 (Percent)| Zone relative humidity set point
Dehumidification Status| AI: 279 : 95 (No_Units)| Dehumidification status
Return Air Temperature| AI: 281 :64 (Deg. F)| Return air temperature
Building Static Pressure| AI: 282 : 64 (Inches of water)| Analog Input 2 (GP1 − VAV Bldg Static)
Duct Static Pressure| AI: 283 : 64 (Inches of water)| Analog Input 1 (GP1 − VAV Supply Static)
---|---|---
Exhaust Fan Status| AI: 285 :98 (Percent)| Exhaust fan status
Controller Online| B1:100 :95 (No_Units)| IMC Communicating

Zone Sensor Setpoints

The IMC typically uses four setpoints and the zone temperature to operate the unit when a zone sensor is installed.
Because the BACnet network provides a single setpoint input, the IMC will use the zone temperature setpoint and ECTO 6.15 to determine the heat / cool setpoint in the occupied mode. During the unoccupied mode, the IMC will se the zone temperature setpoint and the difference between ECTO 6.05 and 6.03.
See figure 5 for an example of setpoints when the IMC is operating using ECTO default values.

IMC Alarm Codes See the IMC user guide for a list of alarm codes.

Interpretation Of Data points

IMC BACnet® Properties – Value_Decoding

Value = 0 − 1
0: Lennox IMC is not communicating.
1: Lennox IMC is communicating.

Set the application mode input to Value.
The IMC controller can be set locally during commissioning to operate in either of two modes: remote zone sensor control mode (with local or remote zone sensor), or remote thermostat control mode. Several application mode command  values are recognized by either IMC mode, while some can only be used when the IMC is in the remote thermostat control mode.

Common Application Mode Values

The four command groups (0−9, 255), (208−209), (216−218), and (224−236, see below) are independent of each other.
Selecting a command from one group does not affect any previously sent command from another group. Except for OFF and RESET, which also set FAN AUTO, EXHAUST AUTO, and heat/cool demand IDLE.
AUTO is the default application mode input. When in a remote zone sensor mode, AUTO allows the IMC control to generate heating and cooling demands based on zone temperature and zone temperature setpoint. Auxiliary functions such as dehumidification or emergency override (i.e. smoke mode) will still operate as needed. Also the blower and exhaust fan fuctions operate.
HEAT and COOL allow the servicing of only heating or cooling demands. These set a mode only, and do not generate a demand.
Application mode OFF is a unit−disable state, causing the controller to become idle, and clearing all outputs and timers.
All outputs are kept off while application mode is OFF.
Application mode FAN ONLY disables heating and cooling operation. No effect on fan operation. Return to normal operation with UTO, HEAT, or COOL.
Application modes FAN ON and FAN AUTO are used to turn on the main unit fan (blower), or return it to automatic operation.
Application modes EXHAUST ON, EXHAUST OFF, and EXHAUST AUTO are used to turn on/off a power exhaust fan, or to return it to automatic operation. The IMC may delay up to 30 seconds before responding to an exhaust  command.

Application mode RESET causes the system to reset itself and go through the controller’s startup and initialization routines. This takes about 8 seconds in an IMC controller, during which time the analog and digital inputs are settling to correct values. The controller will return to AUTO operation.
AUTO, FAN AUTO and EXHAUST AUTO are the defaults after reset.
Application Modes Specific To Remote Thermostat Operation
These values are only recognized if the IMC control is placed in a remote thermostat mode of operation (set locally during commissioning).

For all $Ex values the fan runs if it is already on, otherwise the fan turns on after a fan on−delay. For $E0 the fan turns off after a fan off−delay.
COOL2 and COOL3 are equivalent unless 3−stage cooling has been selected locally at the controller during commissioning.
HEAT2 and HEAT3 are equivalent except in heat pump equipment types, when HEAT2 acts as emergency heat”, running auxiliary strip heat and turning  off the compressor(s). So in a heat pump, normal heating is commanded using
HEAT1 or HEAT3.
If a mode not defined in the above list is sent, then the application mode is not changed.
When an IMC is commissioned for BACnet® gateway remote thermostat operation, it will wait for 5 minutes following startup to receive application mode data. The IMC will remain in AUTO mode until data is received, or until the 5 minute period has expired.
If 5 minutes passes without data being received, then the IMC will enter the backup mode of operation (set locally during commissioning).
It is recommended that the application mode data be updated at intervals of no more than 2 minutes to be sure that a single missed−data event will not constitute an application mode data failure. Any application mode data will serve as a valid update; either common or remote thermostat values.
If application mode data appears while the IMC is in a backup mode, then the IMC will reset and normal operation will resume.

Value = 0 − 255
0 −100: Set the minimum position of the outdoor air economizer damper; % open.
101 − 255: Relinquish to local control. Min damper position depends on the setting in IMC ECTO 5.24: ECTO
5.24=101: Min damper position set by potentiometer on economizer control.
<101: Min damper position set by ECTO 5.24.
The minimum damper position is only effective when the system is occupied and the main blower is running. Otherwise the damper remains closed.

Value = 0−255
0: space occupied
1: space unoccupied (IMC does not support; gives auto operation)
2: refresh space occupied timer defined at local controller
3−255: auto; clear timer and return to occupancy scheduler state

Object Name:
Occupancy Scheduler Control
Object Type: AO (write− datatype unsigned)
Object ID: 104
Object Units: ( 95) No_Units
Value = 0 − 255

Object Name: Occupancy Sensor Input
Object Type: AO (write− datatype unsigned)
Object ID: 107
Object Units: ( 95) No_Units
Value = 0 − 255
0: occupancy sensor indicates space occupied
1: occupancy sensor indicates space unoccupied (IMC does not support; gives auto operation)
2−255: auto; return to occupancy scheduler state
The occupancy inputs are logically OR”; if any one is OCCUPIED” then the space is occupied, otherwise the space is UNOCCUPIED”. No single input can force the space UNOCCUPIED”.

Object Name: Space Dehumidification Setpt
Object Type: AO (write− datatype unsigned)
Object ID: 108
Object Units: ( 98) Percent
Value = 0 − 100
0−100: % relative humidity setpoint
Dehumidification begins when the effective space relative humidity rises to this setpoint value.
Dehumidification ends when the effective space relative humidity reaches falls below this setpoint value minus a dehumidification deadband that is typically 3%. The deadband value is set locally during commissioning.

Object Name: Temperature Setpoint (abs)
Object Type: AO (write− datatype real)
Object ID: 109
Object Units: ( 64) Degrees−Fahrenheit
Value = 36.25 – 100.00 degF, in 0.25 degF increments

The single−point Temperature Setpoint (abs)” (including offset; see below) is converted locally to occupied and unoccupied heating and cooling setpoints. The occupied and unoccupied heating and cooling setpoints are computed to be centered (if possible) on the effective single−point setpoint. This is done while preserving the occupied and unoccupied deadbands, as well as any local restrictions on minimum or maximum values.
The occupied heat/cool auto−changeover deadband value is set locally during commissioning.
The unoccupied heat/cool auto−changeover deadband value is set locally during commissioning by adjusting the backup unoccupied heating and cooling setpoints. The difference between these setpoints will be used as the unoccupied heat/cool auto−changeover deadband value.

Object Name: Temperature Setpoint Offset
Object Type: AO (write− datatype real)
Object ID: 110
Object Units: ( 64) Degrees−Fahrenheit
Value = −32.00 – 31.75 degF, in 0.25 degF increments
A signed value added to the Temperature Setpoint (abs) value to provide an effective temperature setpoint. See above regarding deadbands and limits.

Object Name: Space Temperature Input
Object Type: AO (write− datatype real)
Object ID: 113
Object Units: ( 64) Degrees−Fahrenheit
Value = 36.25 – 100.00 degF, in 0.25 degF increments
A network value for the space temperature. Heating and cooling demands are generated based on the Space Temperature Input”, and the Temperature Setpoint (abs)” and Temperature Setpoint Offset” values. See above.
When an IMC is commissioned for BACnet® gateway remote room sensor operation, it will wait for 5 minutes following startup to receive space temperature data. The IMC will remain in a no−run mode until data is received, or until the  5 minute period has expired.
If 5 minutes passes without data being received, then the IMC begins to use local data for the space temperature. If a local sensor is connected then it will be used. If not, then a failed−sensor error is recorded and the IMC will enter the
backup mode of operation (set locally during commissioning).
It is recommended that network data be updated at intervals of no more than 2 minutes to be sure that a single missed data event will not constitute a data update failure.
If data appears after a sensor failure is processed, it will be treated as an intermittent sensor. Normal operation will resume. If the IMC is in a backup mode, then it will reset before resuming.

Set the emergency mode defined by Value, decoded as:

Value| alue  Mode| Supply Fan| Exhaust Fan| Outdoor Damper
---|---|---|---|---
0| NORMAL| auto| auto| auto
1| PRESSURIZE| on| off| open
2| DEPRESSURIZE| off| on (speed)| closed
3| PURGE| on| on (speed)| open
4| SHUTDOWN| off| off| closed
5| FIRE| | |
6| 6 DEPRESSURIZE| off| on (pressure)| closed
7| PURGE| on| on (pressure)| open

7| NUL (normal)| auto| auto| auto

auto − normal operation
(speed) − exhaust fan runs at speed pre−selected at equipment
(pressure) − exhaust fan runs to maintain building press setpoint; local or remote
Mode 5, FIRE, is a locally defined operation (set at commissioning).
For units without VFD exhaust fans, modes 6−7 are the same as 2−3.
Emergency Override Control” input takes precedence over local smoke input.

Object Name: Compressor Enable Control
Object Type: AO (write− datatype unsigned)
Object ID: 115
Object Units: ( 98) Percent

Value = 0 − 255
0: output disabled
1−100: output limited to 1 – 100% of maximum
101−255: maximum output permitted
The following table shows the Value where the indicated compressor stage is disabled, for equipment having the indicated maximum number of compressor stages:

Object Name: Building Static Setpoint
Object Type: AO (write− datatype real)
Object ID: 124
Object Units: ( 58) Inches−of−water
Value = −0.5 − 0.5 inWC
The setpoint for control of building static pressure, in inches of water column. The exhaust blower is cycled or, if a VFD is used, its speed is varied to maintain this value. The setpoint can be selected from the range of −0.5 to +0.5 inches  f
water column.

Object Name: Discharge Air Cooling Setpoint
Object Type: AO (write− datatype real)
Object ID: 125
Object Units: ( 64) Degrees−Fahrenheit
Value = 40 − 80 degF, and −9 degF
The setpoint for control of discharge (or supply) air temperature during cooling. When the controller is in the correct mode of operation, sending this setpoint will cause cooling components to cycle, or vary their output, in order to  maintain this temperature in the leaving air stream. The setpoint can be selected from the range of 40 to 80 degrees Fahrenheit. Selecting a value of −9 degF causes the control to revert to the use of its locally programmed setpoint.

Object Name: Discharge Air Heating Setpoint
Object Type: AO (write− datatype real)
Object ID: 126
Object Units: ( 64) Degrees−Fahrenheit
Value = 80 − 140 degF, and −9 degF
The setpoint for control of discharge (or supply) air temperature during heating. When the controller is in the correct mode of operation, sending this setpoint will cause heating components to cycle, or vary their output, in order to maintain this temperature in the leaving air stream. The setpoint can be selected from the range of 80 to 140 degrees Fahrenheit. Selecting a value of −9 degF causes the control to revert to the use of its locally programmed setpoint.

Value = 0 − 255
0 − 100: Set the supply fan capacity as a % of maximum speed.
101 − 255: Relinquish to local control. Supply fan capacity depends on IMC ECTO values.
Supply fan capacity is only effective when the main blower is running.

Object Name: Unit Status
Object Type: AI (read)
Object ID: 232
Object Units: ( 95) No_Units
Value = 0 − 255
1 –HVAC heat.
2 – HVAC morning warmup.
3 – HVAC cool.
5 – HVAC pre−cool.
6 – HVAC off.
7 – HVAC test.
8 – HVAC emergency heat.
9 – HVAC fan only.
12 – HVAC max heat.
14 – HVAC dehumidification.
129 – HVAC fresh air heating.
131 – HVAC fresh air cooling.
145 – HVAC defrost compressor 1.
161 – HVAC defrost compressor 2.
177 – HVAC defrost compressor 1 & 2.
These are the currently defined IMC unit status.

Object Name: Space Temperature
Object Type: AI (read)
Object ID: 239
Object Units: ( 64) Degrees−Fahrenheit
Value = 63.75 – 100.00 degF, in 0.25 degF increments

Space temperature from local IMC sensor, or from Space Temperature Input”.
This is the actual value being used by the IMC. Its source is either a locally wired temperature sensor (see Local Space Temperature”) or the network input (see Space Temperature Input”).

Object Name: Discharge Air Temperature
Object Type: AI (read)
Object ID: 240
Object Units: ( 64) Degrees−Fahrenheit
Value = −8.7 – 164.4 degF, in 0.7 degF increments
Discharge air temperature measurement from IMC sensor.

Object Name: Effective Occupancy
Object Type: AI (read)
Object ID: 241
Object Units: ( 95) No_Units
Value = 0 − 2
0: space occupied
1: space unoccupied
2: space occupied (timed override)
The occupancy override timer is established locally for each controller during system commissioning.
The Effective Occupancy” depends on the Occupancy Scheduler Control”, the Occupancy Override Control”, and the Occupancy Sensor Input. The Effective Occupancy” is occupied if any of these inputs are in the occupied state. Otherwise Effective Occupancy” is unoccupied.
The local IMC occupied input is ignored when a BACnet® module is used.

Object Name: Duct Static Pressure
Object Type: AI (read)
Object ID: 283
Object Units: ( 58) Inches−of−water
Value = 0.00 – 5.00 inWC, in 0.02 inWC increments
Duct (supply) static pressure measurement from IMC sensor.

Object Name: Exhaust Fan Status
Object Type: AI (read)
Object ID: 285
Object Units: ( 98) Percent
Value = 0 – 100
0: Exhaust fan off.
1: Exhaust fan on (single−speed fan).
2 − 100: Exhaust fan on (variable−speed fan; percent of full speed).

BACnet® Protocol Implementation Conformance (PIC) Statement
Date: January 30, 2008
Vendor Name: Lennox Industries, Inc.
Product Name: IMC BACnet
Module
Product Model Number: C0CTRL50AE1L
Firmware Revision: Lennox 1.03m, BACnet MSTP 1.15j
BACnet Protocol Revision: 1.2 ANSI/ASHRAE 135−2001

Product Description
The Integrated Modular Control (IMC) with optional IMC BACnet Module is a microprocessor−based unit controller designed to control Lennox’ L Series and S−Class gas/electric, electric/electric and heat pump rooftop units.

BACnet® Standardized Device Profile (Annex L)
BACnet Operator Workstation (B−OWS)
BACnet Building Controller (B−BC)
BACnet Advanced Application Controller (B−AAC)
BACnet Application Specific Controller (B−ASC)
BACnet Smart Sensor (B−SS)
BACnet Smart Actuator (B−SA)

BACnet® Interoperability Building Blocks (BIBBs) Supported (Annex K)
DS−RP−B, DS−WP−B, DM−DDB−B, DS−RPM−B, DM−DOB−B
Segmentation Capability None
Standard Object Types Supported

Device Object
Analog Input
Analog Output
Analog Value
Binary Input
Binary Output
Binary Value
File
Multi−State Input
Multi−State Output

Data Link Layer Options
BACnet
IP, (Annex J)
BACnet IP, (Annex J), Foreign Device
ISO 8802−3, Ethernet (Clause 7)
ANSI/ATA 878.1, 2.5 Mb. ARCNET (Clause 8)
ANSI/ATA 878.1, RS−485 ARCNET (Clause 8), baud rate(s)
MS/TP main (Clause 9), baud rate(s): 38.4K
MS/TP sub (Clause 9), baud rate(s):
Point−To−Point, EIA 232 (Clause 10), baud rate(s):
Point−To−Point, modem, (Clause 10), baud rate(s):
LonTalk, (Clause 11), medium:
Other:

Device Address Binding
Static Device Binding: Yes No

Character Sets Supported
ANSI X3.4
IBM /Microsoft DBCS
ISO 8859−1
ISO 10646 (UCS−2)
ISO 10646 (UCS−4)
JIS C 6226

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