ACI I0000929 Modbus Immersion Series Instruction Manual
- June 5, 2024
- ACI
Table of Contents
BACnet / Modbus IMMERSION SERIES
Installation & Operation Instructions
Phone: 1-888-967-5224
Website: workaci.com
GENERAL INFORMATION
The BACnet MS/TP / Modbus RTU Immersion Series sensor is designed for use with electronic controllers in commercial heating and cooling building management systems. The ACI BACnet MS/TP / Modbus RTU Immersion Series sensor can be ordered to monitor the temperature in commercial HVAC pipes. It uses BACnet MS/TP or Modbus for RTU for physical connection to a BAS or controller has dip switches to set addresses and baud rate, parity, and stop bits (Modbus RTU only), and has onboard end-of-line termination. There is no analog output.
WIRING INSTRUCTIONS
The BACnet/Modbus RTU Immersion Series temperature sensor has a depluggable
terminal block located on the front of the PCB. For ease of wiring, we
recommend removing the block, wiring, and reattaching before mounting. 16 to
22 AWGtwo conductor shielded cable is recommended for powering the sensors.
ACI recommends using Belden 3105 or a compatible cable for RS-485
communication wiring. This wire has 120-ohm input impendence. The terminal
blocks allow for (1) or (2) wires to be connected in each position for daisy-
chaining. Daisy chain the RS-485 wiring and does not use “Star” or “T” wiring.
Avoid running communication wires next to AC line voltage wires. These can be
sources of noise that can affect signal quality.
PRECAUTIONS
- Remove power before wiring. Never connect or disconnect wiring with power applied.
- It is recommended you use an isolated UL-listed class 2 transformer when powering the unit with 24 VAC. Failure to wire the devices with the correct polarity when sharing transformers may result in damage to any device powered by the shared transformer.
FIGURE 1 : ENCLOSURE DIMENSIONS
FIGURE 2 : LAYOUT
TABLE 1 : WIRING CONNECTIONS
TERMINAL BLOCKS | CONNECTIONS |
---|---|
+V | Power Supply Positive 12-36 VDC / 24 VAC |
GN | Power Supply Common or Ground |
D- | EIA-485 Data Negative |
D+ | EIA-485 Data Positive |
PRECAUTIONS (Continued)
- If the 24 VDC or 24VAC power is shared with devices that have coils such as relays, solenoids, or other inductors, each coil must have a MOV, DC/AC Transport, Transient Voltage Suppressor (ACI Part: 142583), or diode placed across the coil or inductor. The cathode, or banded side of the DC Transorb or diode, connects to the positive side of the power supply. Without these snubbers, coils produce very large voltage spikes when de-energizing which can cause malfunction or destruction of electronic circuits.
For optimal temperature readings, follow these tips:
-
The sensor thermowell should be installed against the flow of the water, where water temperature is well mixed (no stratification).
*Reference FIGURE 4 -
Make sure the entire thermowell is immersed. If the thermowell is longer than the pipe diameter, the thermowell should be installed in an elbow or Tee.
-
Apply thermal grease to the end of the probe before installation into thermowell (ACI Item #102595).
-
The tip of the thermowell should be located in the middle of the pipe.
TABLE 2: PROBE & INSERTION LENGTH
ACI PART # | IMMERSION LENGTH | PROBE LENGTH |
---|---|---|
A/BN2110-INW2.5-PB | 2.5” (63.50 mm) | 4.31” (109.47 mm) +/- 0.13” (3.30 mm) |
A/BN2110-INW4-PB | 4.0“ (101.60 mm) | 5.81“ (147.57 mm) +/- 0.13” (3.30 mm) |
A/BN2110-INW6-PB | 6.25” (158.75 mm) | 7.81” (198.37 mm) +/- 0.13” (3.30 mm) |
FIGURE 3 : PROBE and IMMERSION
FIGURE 4 : ASSEMBLY
FIGURE 5: TEE MOUNT ASSEMBLY
THERMOWELL INSTALLATION
ACI’s standard Immersion sensors are made to install into a ½” NPT female
thread. Typically a Threadolet or Tee is installed into the pipe, but a hole
can also be drilled and tapped. The pipe/system will need to be drained,
unless a Hot Tap is being used. The recommended drill size is 23/32 in. (18
mm). Drill the hole, and tap the hole with ½”-14NPT.
Always use proper thread sealants on tapered pipe threads of the thermowell.
Screw the thermowell into the Threadolet, Tee, or tapped hole, using a wrench
to tighten it firmly. Refill the system and check for leaks.
Best practice is to apply thermal grease to the end of the probe, but not
required. Insert and push the sensor probe into the thermowell. Turn the
sensor probe assembly clockwise to tighten down completely.
Open the cover of the enclosure. Refer to the wiring instructions (p. 1) to
make necessary connections. After wiring, attach the cover to the enclosure.
FIGURE 6 : THREADOLET ASSEMBLY
FIGURE 7 : ELBOW ASSEMBLY
FLOW DIRECTION
PROBE INSERTION
The “-INW” includes a standard ½” NPS process thread to be used with a
machined thermowell or previously installed thermowell. Verify the existing
thermowell insertion length of the pipe is suitable for your selected
Immersion.
If the length of the probe is too large, the probe may be pressed into its
enclosure – up to an inch of
clearance.
Note: *Fabricated (welded) thermowells (-I) are not intended for moving
water or high-pressure service. Fluid velocity and wake frequency are primary
factors in good failure. Machined thermowells (-IM) should be used in these
types of applications. Fabricated thermowells are intended for the tank, or
low to no now, applications.
BACnet MS/TP and Modbus RTU INTERFACE
The BACnet Master-Slave/Token-Passing (MS/TP) and Modbus Remote Terminal Unit (RTU) data link protocol uses EIA-485 as a two-wire, daisy chain network. A branch is a discrete chain of devices connected to a controller. The max number of devices per segment is 32, as per the BACnet and Modbus specifications. 4000 ft (1219.2 m) is the maximum recommended length for a segment, which includes all devices from the controller to the last device in the daisy chain.
BACnet MS/TP and Modbus RTU INTERFACE (Continued)
BACnet or Modbus RTU protocol selection is done via SW4 switch. Place
dipswitch #4 to the OFF position for BACnet and the ON position for Modbus.
Refer to FIGURE 8.
ACI’s BACnet sensors are master devices. Only master nodes are allowed to send
and receive tokens on the MSTP network.
ACI’s Modbus RTU sensors are slave devices. Only one master is connected to
the bus and several slave nodes are connected to the same trunk. The Master
initiates communication. The slave nodes only respond to a request from the
Master. Slave nodes do not communicate with each other.
Each branch must have all devices connected with (+) connected to (+) and (-)
connected to (-). If a shielded cable is used, this is not to be connected to
the devices. The shielded cable should only be connected on one end to earth
ground, usually at the controller. The start and end of each branch should
have a termination resistor at the device level or at the controller.
Each device must be configured for the correct baud rate and have a unique
address in each branch. The baud rate for the branch is set by the controller.
This product has auto-baud for ease of network configuration but setting the
baud rate using the DIP switches is recommended. Note: Auto-baud feature does
not function when Modbus is the selected protocol.
FIGURE 8 : SW4 DIPSWITCH SETTINGS
| DIP 1 – PAR2 (only applies to Modbus)
DIP 2 – PAR1(only applies to Modbus)
DIP 3 – OPEN (For Future Use)
DIP 4 — OFF is BACNET, ON is MODBUS
---|---
BAUD RATE SELECTION
By default, BACnet Protocol and Auto-Baud are factory set. If the sensor is
field adjusted for Modbus RTU, the baud rate should be selected at this time
to match the Master configuration. If Modbus RTU protocol is selected it is
recommended the sensor’s unique address be selected at this time. Switches
8-10 are used to set the BACnet and Modbus baud rate. Refer to TABLE 3 for
switch settings. Where (0) is OFF and (1) is ON.
If the system’s baud rate is known, it is recommended to set the specific baud
rate to match the system. If the device is powered when a change is made, the
device must be power cycled or reset for changes in the baud rate to be made.
TABLE 3: BAUD RATE SELECTION
BAUD RATE | SW 8 | SW 9 | SW 10 |
---|---|---|---|
Auto-Baud | 0 | 0 | 0 |
9600 | 0 | 0 | 1 |
19200 | 0 | 1 | 0 |
38400 | 0 | 1 | 1 |
57600 | 1 | 0 | 0 |
76800 | 1 | 0 | 1 |
Reserved | 1 | 1 | 0 |
**Note: Auto-Baud not available for Modbus RTU.
EOL TERMINATION RESISTANCE SELECTION
RS-485 requires that the last device in a chain have a termination resistor. This is controlled using a jumper in the EN (enabled) position marked in FIGURE 9. When the jumper is set to EN (enabled), a 120Ω resistance is added in parallel to the data line. When the jumper is set to DIS (disable), the resistance is not added. By default, the jumper is placed in the DIS (disabled) position.
FIGURE 9 : EOL TERMINATION JUMPERS
RESET
The reset button can be used to reset the device without disconnecting power. The location of this button is shown in FIGURE 2 (P.1).
LED INFORMATION
One LED indicates four statuses. Solid green shows that power is good, but no data is transmitting. A solid Amber indicates that auto-baud is set and no data has been received to set a baud rate. Green/Amber flashing indicates data is being transmitted or received. Solid Red LED status indicates an error state, usually loss of communication on the network. If BACnet is the selected protocol, and this status remains for 10 times the APDU timeout, the device will automatically reset. If this state remains longer than that, reset the device.
ADDRESS SELECTION
Switches 1-7 are used to set the BACnet and Modbus addressing. Refer to TABLE 4 for switch settings. Each device in a network branch must have a unique address. The value of each position is printed on the board. By default, the address is (0). Note: (0) cannot be used if Modbus RTU protocol is selected and will require a unique address. If the device is powered when a change is made, the device must be power cycled or reset for changes in address to be made.
DEVICE CONFIGURATION THROUGH BACnet
DEVICE INSTANCE
The Device Instance, by default, is 1035000 plus the Address. For example, an
Address of 21 results in a default address of 1035021. This can be changed
once the device is connected to the network, but each device instance must be
unique within the network, not just this segment.
DEVICE NAME
By default, the device name is based on the type of device and the address.
The device name can be a character string up to 32 characters in length. This
can be changed once the device is connected to the network. For example
Temperature Sensor – 034. The device name must be unique throughout the entire
BACnet network, not just this segment.
TEST MODE BACnet
For the Sensor objects (AI0 and AI1), a test mode can be set by writing the
Boolean value true to the “out-of-service” property. Then the present value
can be set to any valid test value the user requires. This allows a user to
test reactions to specific values returned by this device.
DEVICE LOCATION
The device location is optional but is intended to allow for further
definition of the device’s location. The device location can be a character
string up to 64 characters in length.
DEVICE DESCRIPTION
By default, the device description is optional but is intended to allow for
further information about the device or its environment. The device location
can be a character string up to 64 characters in length.
TABLE 4 : ADDRESS SELECTION
ADDRESS
| SW 1
(64)
| SW 2
(32)
| SW 3
(16)
| SW 4
(8)
| SW 5
(4)
| SW 6
(2)
| SW 7
(1)
---|---|---|---|---|---|---|---
0| 0| 0| 0| 0| 0| 0| 0
1| 0| 0| 0| 0| 0| 0| 1
12| 0| 0| 0| 1| 1| 0| 0
TEMPERATURE UNITS CONFIGURATION
For temperature, the units of measure can be configured using BACnet. By writing to the unit property of the temperature sensor (AI0), the reported temperature units can be changed. TABLE 5shows the values to write.
TABLE 5 : UNIT SETTING
UNITS | VALUE |
---|---|
°F | 64 |
K | 63 |
°C | 62 |
TEMPERATURE AND RH OFFSET
This device allows for a temperature offset of +/-5C (9F) and an RH offset of
+/-10%. By default, these values are set to 0, meaning no offset is added.
These are set by writing to the present value of the Temperature Calibration
Offset (AV0) or RH Calibration Offset (AV1). The value is written must be
within the specified range or an error will be returned. To set back to
factory settings, write any changed values to 0.
TABLE 6: BACnet OBJECT TABLE
OBJECT TYPE| OBJECT ID| OBJECT NAME| RANGE|
BACnet ENGINEERING UNITS| PIC STATEMENT QR
---|---|---|---|---|---
Device| – – – – – – – – – –| BN211x0| 0-4194302| – – – – – – – – – – – – – – –
– – – – – – – – – – –|
https://www.workaci.com/sites/default/files/category-files/I0000808.pdf
Analog
Inputs
| AI-0| Temperature Sensor| 34.7 – 122.0| degrees-Fahrenheit (64) – default
AI-1| RH Sensor| 0.0 – 95.0| percent-relative-humidity (29)
Analog
Values
| AV-0| Temperature
Calibration Offset
| -9.0 – 9.0| delta-degrees-Fahrenheit (120)
| AV-1| RH Calibration Offset| -10.0 -10.0| percent-relative-humidity (29)
Note: The table shows all objects for Temperature and RH. If you have a Temperature only model, the RH objects(AI-1 and AV-1) will not be present. If you have a RH only model, the Temperature objects (AI-0 and AV-0) will not be present.
DEVICE CONFIGURATION THROUGH MODBUS RTU
MODBUS RTU DATA BITS, PARITY, AND STOP BITS SELECTION
Confirm Modbus Protocol is selected via dipswitch #4 on SW4 – see FIGURE 8
(P.4). The device that requests information is called the Modbus Master and
the devices giving the information are Modbus Slaves. The Modbus sensors are
slave devices and the number of Data Bits needs to be the same as in the
Master device configuration. ACI’s Modbus RTU sensors utilize 8 data bits
during communication exchange.
Parity and stop bit selection is performed via the SW4 switch located on the
board. Dipswtiches #1 and #2 are adjusted to select the parity and stop
TABLE 7 : PARITY AND STOP BITS
PAR 2 | PAR 1 | Mode (Databits-Parity-Stop Bits) |
---|---|---|
0 | 0 | 8-Even-1 |
0 | 1 | 8-Odd-1 |
1 | 0 | 8-None-2 |
1 | 1 | 8-None-1 (Non-Standard) |
bits – see TABLE 7. Where (0) is OFF and (1) is ON. If BACnet protocol is
selected these dipswitches are irrelevant.
TEST MODE Modbus RTU
There are 5 data values in test mode. Coil 1001, Holding Registers (HR) 1001
and 1002, and the Input Registers (IR) 0003 and 0004 for Temp and RH values.
When Coil 1001 is enabled, reading IR 0003 and 0004 will respond with the
values in HR 1001 and 1002, otherwise, they will respond with the actual
sensor values. General process for this is to write initial test values to HR
1001 and 1002, Enable Coil 1001, and then read as normal from IR 0003 and
0004. While Coil 1001 is enabled, it is possible to write a change of value to
IR 1001 and 1002, which will be reflected in the next read from IR 0003 and
0004. When testing completed, disable Coil 1001. The status of Coil 1001 and
HR 1001 and 1002 are not persistent between reset/power cycle.
MODBUS RTU MAP
REFERENCE | ADDRESS | NAME | DESCRIPTION |
---|
COILS (CL)
1001| 1000| Test Mode Enable| 0 = Disable Test Mode. IR3 and IR4 will read
with current Sensor Value.
1 = Enable Test Mode. IR3 and IR4 will read with the values stored in HR1001
and HR1002.
INPUT REGISTER (IR)
1| 0| Sensors Present| For each bit location: 0 = Sensor not present 1 =
Sensor present Bit 0 – Temperature Sensor Bit 1 – RH sensor
2| 1| Reserved| N/A
3| 2| Temperature Sensor Value| For example, a value of 312 would represent
31.2 Degrees of the units selected in HR1. Signed Integer.
4| 3| RH Sensor Value| For Example A value of 429 would represent 42.9%
Relative Humidity.
2001| 2000| Temperature Range Min| Temperature range Minimum value (Tenths).
Signed Integer.
2002| 2001| Temperature Range Max| Temperature range Maximum value (Tenths).
Signed Integer.
2003| 2002| RH Range Min| Relative Humidity range Minimum value (Tenths)
2004| 2003| RH Range Max| Relative Humidity range Maximum value (Tenths)
9001| 9000| Unsigned Integer Test Value| Always reads a value of 54321. For
testing proper communication and interpretation of values.
9002| 9001| Signed Integer Test Value| Always reads a value of -12345. For
testing proper communication and interpretation of values.
9003 Thru
9006
| 9002 Thru
9005
| Test String Test Value| Always reads a string value of “-123.45” (Null
terminated). For testing proper communication and interpretation of values.
9007 Thru
9010
| 9006 Thru
9009
| Serial Number| Non-null terminated character string of the Serial Number.
For example, “12345678”
9011 Thru
9016
| 9010 Thru
9015
| Firmware Version| Non-null terminated character string of the Firmware
Version. For example, “02.00.000.90”
HOLDING REGISTER (HR)
1| 0| Temperature Units| Value – Units:
62 – Degrees Celsius 63 – Degrees Kelvin
64 – Degrees Fahrenheit
2| 1| Temperature Offset Value| Temperature Offset Value (Tenths) Signed
Integer.
User can set an offset that will be added to Temperature sensor and reflected
in IR3. Range of -5.0 to 5.0 degrees Celsius/degrees Kelvin (-9.0 to 9.0
degrees Fahrenheit).
For example, writing -16 would add an offset of -1.6 degrees.
3| 2| RH Offset Value| Relative Humidity Offset (Tenths) User can set an
offset that will be added to RH sensor and reflected in IR4. Range of -10.0 to
10.0 %RH.
For example, writing -16 would add an offset of -1.6 %RH.
1001| 1000| Test Mode Temperature Value| User can set what temperature value
(Tenths) that would be returned when reading IR3 and Test Mode is Enabled in
CL1001. For Example -400 would be -40.0.
---|---|---|---
1002| 1001| Test Mode RH Value| User can set what RH value (Tenths) that would
be returned when reading IR4 and Test Mode is Enabled in CL1001.
9001 Thru
9016
| 9000 Thru
9015
| Device Name| Device Name, Device Location, and Device Description are user
settable character strings (Null terminated) that can be used to allow for
system customization and device identification.
For example:
Device Name (Modbus 9001 thru 9016) could be set to a system ID: “S2253”
Device Location (Modbus 9017 thru 9048) could be set to: “Building 5, Floor 2,
Duct 3”
Device Description (Modbus 9049 thru 9080) could be set to: “Cold air return
sensor”
9017 Thru
9048
| 9016 Thru
9047
| Device Location
9049 Thru
9080
| 9048 Thru
9079
| Device Description
PRODUCT SPECIFICATIONS
Supply Voltage:| 12 to 36 VDC / 24 VAC +/- 10%, 50/60 Hz (Reverse
Polarity Protected)
Current Consumption:| 25 mA maximum (0.67 VA)
Operating Temperature Ranges Transmitter:
Sensor:
| **** -22 to 176°F (-30 to 80°C)
-40 to 302°F (-40 to 150°C )
Temperature Measurement Accuracy:| @ 77°F (25°C): +/- 1.0°F (+/-
0.5°C)
Temperature Calibration OKset:| +/- 9°F (+/- 5°C) (Field Configurable)
Communication Protocol:| BACnet MS/TP or Modbus RTU = Field Selectable;
EIA RS-485
Sensor Addresses:| 0 to 127 (0 (Default – Must be changed if Modbus RTU
is selected protocol); Field Selectable)
Supported Baud Rates:| Auto Baud (Default, BACnet Only ), 9600,
19200, 38400, 57600, 76800, 115200
(Field Selectable)
Device Instance Number:| 1035000 + Address (example: Address 127
= 1035127; Field Configurable)
Parity (Modbus RTU)| None/Even/Odd = Field Selectable
Stop Bits (Modbus RTU)| 1 or 2 = Field Selectable
Data Bits (Modbus RTU)| 8
Connections / Wire Size:| Screw Terminal Blocks / 16 AWG
(1.31 mm2) to 22 AWG (0.33 mm2)
Terminal Block Torque Rating:| 0.45 lbf-in (0.5 Nm) nominal
Thermowell Instrument:| ½” NPS (National Pipe Straight) Male Thread
Enclosure Specifications:| “-PB” Enclosure: ABS Plastic, UL94-HB,
Plenum Rated
W.E.E.E. DIRECTIVE
At the end of their useful life the packaging and product should be disposed
of via a suitable recycling center. Do not dispose of with household waste. Do
not burn.
| | |
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BACnet is a registered trademark of ASHRAE. ASHRAE does not endorse, approve or test products for compliance with ASHRAE standards. Compliance of listed products to the requirements of ASHRAE Standard 135 is the responsibility of BACnet International (BI). BTL is a registered trademark of BACnet International.
Automation Components, Inc.
2305 Pleasant View Road | Middleton, WI 53562
Phone: 1-888-967-5224 |
Website: workaci.com Version: 4.0
I0000929
Documents / Resources
| ACI
I0000929 Modbus Immersion
Series
[pdf] Instruction Manual
I0000929 Modbus Immersion Series, I0000929, Modbus Immersion Series
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