Dixell XR170C

Refrigeration controller

The Dixell XR170C controls the compressor, defrost, fans and an alarm or auxiliary relay of a refrigerated cabinet or cold room, with a door switch input and up to three probes. Its built-in RS485 port makes it compatible with EpiSensor Edge over Modbus RTU through a ZMB Modbus interface. EpiSensor's Modbus profile reads the room, evaporator and third probes, the setpoint and the differential.

  • Modbus RTU

Refrigeration controller

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Compatibility

Compatible with EpiSensor Edge over Modbus RTU through a ZMB Modbus interface

Dixell documents a built-in RS485 serial port with Modbus RTU on the XR160C and XR170C, on terminals 20 (-) and 21 (+), with the address set by Adr. A ZMB-31 or ZMB-30 on that port reads the controller and sends the values to the Gateway running Edge. The addresses come from EpiSensor's Modbus profile for the XR170C.

Set Adr first and check the controller is not fitted with the optional 4 to 20 mA output, which uses the same terminals. Dixell's manual prints no register table, so compare the room probe with the display once and record Ptb. Setpoint and parameter writes stay with the refrigeration contractor.

Connect it with

For an XR170C (or XR160C) without the optional 4 to 20 mA output

  • Modbus
  • Wireless
  • Edge
  • Platforms
Refrigeration controller
Interface
Gateway
Edge
Output
XR170CXR170C RS485 terminals 20 (-) and 21 (+)
ZMB-31Modbus RTU to the EpiSensor wireless network
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeModbus client + register map
Customer platformMQTT · API · files
Modbus RTU · RS-485
EpiSensor wireless
Runs locally
Optional onward data
Wire terminal 21 (+) and terminal 20 (-) to the ZMB with shielded twisted pair. Set the ZMB to 9600 bit/s, 8 data bits, no parity and 1 stop bit and poll the controller's Adr address. Any ZMB reads all five starter points; the ZMB-30 also adds its own waterproof probe. The customer-platform output is optional; Edge remains the local system of record.

Specifications

Dixell's manual describes the XR160C and XR170C as 32 x 74 mm microprocessor controllers for medium or low temperature refrigerating units, connectable to a monitoring system through the two terminals of their RS485 serial port. Defrost can be electric, hot gas or thermostatic, with a smart defrost mode.1

Power supply
12 Vac/dc, optional 24 Vac/dc, -10 % +15 %; 3 VA max1
Probe inputs
3 PTC or NTC, configurable; two voltage-free digital inputs1
Measuring range
PTC -50 to 150 °C; NTC -50 to 110 °C1
Accuracy and resolution
±0.3 °C ±1 digit from -40 to 50 °C at 25 °C ambient; 0.1 °C or 1 °F1
Relay outputs
Compressor SPDT 8(3) A; defrost SPDT 8(3) A; fans SPST 8(3) A; alarm or auxiliary SPDT 8(3) A on the XR170C, 250 Vac1
Serial output
RS485 with Modbus RTU on terminals 20 (-) and 21 (+); address Adr 1 to 247, default 11
Housing and protection
32 x 74 mm front, 70 mm deep, 71 x 29 mm panel cut-out; IP65 front1
Operating conditions
0 to 60 °C, 20 to 85 % RH non-condensing1

Interface

This register map is for the XR170C. XR160C and XR570C have their own interfaces and are not covered here.

Communication settings

Protocol
Modbus RTU on the built-in RS485 terminals (20 -, 21 +)
Unit address
Parameter Adr, 1 to 247
Baud rate
9600 bit/s
Data bits, parity and stop bits
8 data bits, no parity, 1 stop bit
Read with
FC03 (holding registers)
Addresses
Zero-based PDU addresses, as sent on the bus
Route into Edge
ZMB-31 or ZMB-30 on terminals 20 and 21 at 9600 bit/s 8N1.

From EpiSensor Modbus profile for the Dixell XR170C4.

Register map

Download
PointAddressHexFormatScaleUnit
Room probe P1 256 0x0100 INT16 ×0.1 °C
Evaporator probe P2 258 0x0102 INT16 ×0.1 °C
Third probe P3 (display or condenser) 260 0x0104 INT16 ×0.1 °C
Differential Hy 769 0x0301 UINT16 ×0.1 °C
Setpoint 876 0x036C INT16 ×0.1 °C

Download the XR170C register map as CSV

Assessment

XR170C on its built-in RS485 port, read with EpiSensor's Modbus profile. Relay, alarm and door states are outside this starter map.

InteroperabilitySupported with conditions
Dixell documents Modbus RTU on built-in RS485. The register addresses come from EpiSensor's profile, not a published Dixell table.14
AccuracySupported with conditions
Dixell states ±0.3 °C ±1 digit from -40 to 50 °C. The room probe is placed for control, so a product record needs an independent probe.1
SecurityNot yet assessed
The manual describes a keyboard lock but no protection on the serial port.1
ReliabilitySupported with conditions
The RS485 port is on the controller's own terminals and the manual lists probe failure alarms. Edge timestamps each read, so a lost bus shows as missing data.1
RuggednessSupported with conditions
IP65 front, rated 0 to 60 °C, for panel mounting.1
ScalabilityWell supported
Built-in RS485 with addresses from 1 to 247 lets several controllers share one bus.1
LifecycleSupported with conditions
Copeland still hosts the XR170C manual. The controller reports its parameter table code as Ptb, so record it with the software release rEL.13

Edge template

This JSON file supplies the register map. Applying it to an existing meter replaces its sensor list while retaining the site connection, unit ID and enable state.

ModelConnectionPointsVersionUpdatedDownload
XR170C Built-in RS485 on terminals 20 (-) and 21 (+), Modbus RTU, address Adr, 1 to 247, default 1 5 1.0.0 Download

Downloads need a signed-in account with Edge download access.

Use the template in Edge

  1. Import the JSON file

    In Edge, open Settings, then Devices and Templates. Choose Import JSON and select the downloaded file. Confirm that the model and template name match your device.

  2. Load the map for your meter

    For a new Modbus device, use Load Template before entering the manufacturer or model; it fills those fields and the register list. Set the name, site connection and unit ID, check the polling enable state, then test before saving. For an existing device, apply only to the matching model; this replaces its sensor list but retains its connection, unit ID and enable state.

  3. Test a reading

    Use Test in the wizard and compare a known reading with the meter display. Check its unit, sign and scale, then confirm that timestamps keep advancing. These starter maps are read-only and leave exports off until you configure them.

Setup

Read the evaporator probe

EpiSensor's Modbus profile places the XR170C evaporator probe at holding register 258 (0x0102) as a signed value in tenths of a degree.

Request PDU
03 01 02 00 01
Address
258 decimal = 0x0102, zero-based, one register
Decode
Signed 16-bit, divide by 10 with rES = de: a synthetic reply of FF 9C is -100, which is -10.0 °C
Compare with
The evaporator probe shown on the display (Prd menu) within a few seconds

Acceptance: Accept the map when the evaporator and room probes agree with the display. The reply bytes are an example, not a captured reply. During defrost the evaporator probe rises towards the defrost termination temperature, which is expected.

  1. Check the order code

    Confirm the controller has RS485 on terminals 20 and 21, not the optional 4 to 20 mA output on the same terminals.

  2. Set the address

    Set Adr (1 to 247) to a unique address for the bus and note Ptb. Check rES: the tenths decode applies with rES = de in °C.

  3. Wire terminals 20 and 21 to the ZMB

    Connect terminal 21 (+) and terminal 20 (-) to the ZMB with shielded twisted pair, terminate both ends, and set the ZMB to 9600 bit/s, 8 data bits, no parity, 1 stop bit.

  4. Read the room probe once

    Read holding register 256 (0x0100) with FC03 and divide by 10. Compare it with the display, then add the evaporator and third probes, Hy and the setpoint.

  5. Place the record probe

    Fit an independent probe at the warmest product position and set Edge alarm limits and delays to the site's HACCP plan.

Common questions

Does the XR170C need a converter for Modbus?
No. The XR160C and XR170C have a built-in RS485 port with Modbus RTU on terminals 20 (-) and 21 (+). Wire it straight to the ZMB.1
Where do the register addresses come from?
From EpiSensor's Modbus profile for the XR170C. Dixell's manual prints no register table, so compare the room probe with the display before saving the map.14
What is the third probe at 260?
EpiSensor's Modbus profile calls it the display temperature. The XR170C's third probe input can be set for display or condenser use, so name the point after the installed function.14
Can a ZMB-30 read the whole starter map?
Yes. Every ZMB reads 8 or more registers, up to 16 or more depending on the model, so the five starter points fit on one. The ZMB-30 also adds its own waterproof probe.5

Sources

  1. XR160C and XR170C installing and operating instructions, cod. 1592008230 rel. 1.0 (opens in a new tab) (PDF) Dixell (Copeland)
  2. XR570C installing and operating instructions, cod. 1592008310 rel. 1.0 (opens in a new tab) (PDF) Dixell (Copeland)
  3. Dixell brand page (opens in a new tab) Copeland
  4. EpiSensor Modbus profile for the Dixell XR170C (opens in a new tab) EpiSensor
  5. ZMB-3X Modbus interface datasheet EPI-195-00 (opens in a new tab) (PDF) EpiSensor

Further reading

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