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Eliwell EWRC 300/500/5000 NT

Eliwell EWRC 300/500/5000 NT cold room controller in TapHome over Modbus RTU on RS-485, through the optional Eliwell RS-485 plug-in module. Cold room and evaporator probe temperatures, setpoint, high and low alarm thresholds, operating state, alarms, and commands for on/off, economy mode, manual defrost and alarm acknowledgement.

Modbus RTU6 devicesRevision 1.0 Last updated: November 12, 2026

Submitted by Adam Tížik

Eliwell EWRC 300/500/5000 NT

Import into the TapHome appHardware › Modbus › Add from template

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Integration guide

The Eliwell EWRC 300/500/5000 NT (Coldface) is a controller for static or ventilated cold rooms, positive or negative, with 3 or 5 configurable relays depending on the model and up to three temperature probes. TapHome communicates with it over Modbus RTU on an RS-485 bus, through Eliwell’s optional RS-485 plug-in module.

The template reads the cold room and evaporator probe temperatures, writes the regulation setpoint and the high and low alarm thresholds, shows the operating state and the alarms of the controller, and sends commands such as on/off, economy mode, manual defrost and alarm acknowledgement.

Hardware connection

The controller has no RS-485 terminals of its own. Its serial port is the TTL port (labelled CARD on the board), which is used for the UNICARD / Copy Card, the HACCP module of RCN models and TelevisSystem. To reach a Modbus master over RS-485, the manufacturer specifies the optional RS-485 plug-in module (TelevisSystem / Modbus), fitted into the plug-in connector on the control board.

Disconnect all power from the controller and from every connected device before removing covers or fitting the module, and confirm with a rated voltage tester that the power is off. Refit all covers before powering the controller back up.

Fitting the RS-485 plug-in module

  1. Fit the module into the plug-in connector, aligning its four posts with the holes in the control board — a misaligned module can damage the equipment.
  2. On the EWRC 5000 NT, first remove the seven screws holding the plastic protection of the board, remove the protective element and cut out the two terminal covers; then mount the module on its spacers and refit the cover.

Wiring to the TapHome RS-485 bus

The module terminal block is marked +, − and G, in two identical groups. Connect + to A and − to B of the TapHome RS-485 bus, and G to the ground of the bus.

Eliwell EWRC 300/500/5000 NT wiring diagram: probe and digital inputs, relay outputs, TTL card port and optional RS-485 module, with terminal table

The manufacturer’s cabling rules for the RS-485 line:

  • Shielded twisted pair, two conductors of 0.5 mm² (AWG 20) plus braid — for example Belden 3105A (120 Ω) or Belden 8762.
  • Use all three conductors: + and − for the signal, G for the braid.
  • Fit a 120 Ω, 1/4 W resistor between + and − at the interface and at the last controller of each branch.
  • The network connected directly to the controller may be up to 1200 m long; repeaters extend it.
  • Keep data cables separate from power lines.

Modbus and Televis must never communicate at the same time on the same serial port. The manufacturer also states that the TTL port and the RS-485 port are not used together: when communicating over RS-485, disconnect the TTL port, and vice versa.

Configuration

Enabling Modbus on the controller

The protocol, address, parity and baud rate are installer parameters in the Add (communication) folder. Their factory defaults depend on the firmware family of the controller (MSK 554 or MSK 812), so read the current values on the display before changing them.

ParameterMeaningValuesFactory defaultRegister
PtSProtocol of serial port COM1t = Televis, d = Modbust (MSK 554), d (MSK 812)49289
AdrModbus address1–250149422
PtyModbus parityn = none, E = even, o = oddn (MSK 554), E (MSK 812)49292
StPModbus stop bits1b, 2b1b49293
bAUBaud rate96 = 9600, 192 = 19200, 384 = 38400 Bd9649421

Data bits are fixed at 8. Over Modbus the registers hold the index of the option (PtS 0 = Televis, 1 = Modbus; Pty and bAU 0/1/2), not the letters shown on the display.

Eliwell EWRC NT Modbus commands and address configuration: parameters PtS, Adr, Pty and bAU

Steps on the controller keypad:

  1. Press and hold SET for about 3 seconds until USr appears.
  2. Use UP / DOWN to select InS and press SET.
  3. Enter the installer password PA2 with UP / DOWN and confirm with SET — the factory value is 15.
  4. Open the Add folder and set PtS to d (Modbus). With the default t the port speaks Televis and does not answer Modbus requests.
  5. Set Adr to a free address on the bus, bAU to 96 (9600 Bd), StP to 1b and Pty as described below. Each value is saved with SET; ESC returns to the normal display.
  6. Switch the controller off and on again — the new communication settings take effect only after the restart.

A parameter map can also be transferred to the controller with a UNICARD or Copy Card instead of the keypad.

The parity on the controller must match the parity of the TapHome RS-485 bus. The template suggests 9600 Bd, 8 data bits, no parity, 1 stop bit. On MSK 554 firmware Pty is n by default and matches; on MSK 812 firmware it is E by default — either set Pty to n, or set the TapHome bus to even parity.

Adding the controller in TapHome

Import the template on the RS-485 bus set to 9600 Bd 8N1 (or to the parity chosen above) and set Modbus Slave ID to the Adr value of the controller (default 1).

Device capabilities

DeviceWhat it doesRegisterAccess
ThermostatCold room temperature (probe 1) and regulation setpoint SEt345 (temperature), 16386 (setpoint)Read / write setpoint
Probe 2 temperatureTemperature of analogue input Pb2347Read
Device stateController on/off with operating details33089, 33092Read
High alarm threshold (HAL)Maximum temperature alarm limit16418Read / write
Low alarm threshold (LAL)Minimum temperature alarm limit16420Read / write

Status and probe values are read from the client table (Modbus function 03); parameters SEt, HAL and LAL from the parameter table, which the manufacturer reads with function 04 and writes with function 22.

Temperatures and setpoint

The thermostat shows the regulation temperature of probe Pb1 — by default the cold room probe — and reads and writes the setpoint SEt. The compressor starts when the Pb1 temperature exceeds SEt + diF (setpoint differential) and stops when it falls below SEt. The setpoint range is limited by the controller parameters LSE (minimum) and HSE (maximum).

Probe 2 temperature reads probe Pb2, which is the evaporator (defrost end) probe in the default configuration. The template divides both probe values by 10.

Device state

The Device state switch is read-only and shows whether the controller is on (bit 1 of register 33089). It also reports:

  • economy mode active
  • light on
  • auxiliary output active
  • compressor 1 running
  • defrost 1 active

Alarm thresholds

HAL and LAL set the high and low temperature alarm thresholds for probe 1; the template writes them in tenths, as the manufacturer’s table specifies. Whether they are absolute temperatures or offsets from the setpoint depends on the controller parameter Att: absolute by default (Att = 0); with relative mode (Att = 1) HAL must be positive and LAL negative. The factory values are 50.0 and −50.0. An alarm clears once the temperature has moved back by the alarm differential AFd.

Alarms

The module reports the active alarms of the controller as errors (registers 33085 and 33084):

CodeAlarm
HA1Probe 1 high temperature threshold exceeded
LA1Probe 1 low temperature threshold exceeded
EALExternal alarm
OPdDoor open
E1Probe 1 error
E2Probe 2 error
E3Probe 3 error
PAPressure switch alarm
ALdRefrigerant leak
E10Clock error

Commands

The module offers these service actions, written to the command registers 33057 and 33058:

ActionRegisterValue
Device on3305764 (bit 6)
Device off33057128 (bit 7)
Economy mode on330574 (bit 2)
Economy mode off330578 (bit 3)
Manual defrost330582 (bit 1)
Alarm acknowledgement330581 (bit 0)

The device names, state names and alarm messages in the template are in Slovak.

Troubleshooting

The controller does not respond

  • Check that PtS is set to d (Modbus) and that the controller was switched off and on after the change.
  • Check that the RS-485 plug-in module is fitted and that nothing communicates on the TTL (CARD) port at the same time.
  • Compare Pty, bAU and StP with the TapHome bus settings, and Adr with the Modbus Slave ID of the module.
  • Check the 120 Ω termination at the ends of the line and the G conductor.

A temperature value is wrong

Check that the probe type set in parameter H00 (PTC or NTC) matches the probes fitted; a wrong probe type gives wrong readings. A change in the configuration folder CnF requires switching the controller off and on again. If probe Pb2 is disabled (H42 = n, as the manufacturer recommends for positive cold rooms), the probe 2 temperature has no meaning.

HA1 or LA1 right after power-on

After power-on the controller excludes the temperature alarms for the time set in parameter PAO (0–10 hours, 3 hours by default). With PAO = 0 the alarms are evaluated immediately, so HA1 or LA1 can appear as soon as the controller starts.

Writing the setpoint has no effect

Check that the new setpoint lies between LSE and HSE on the controller. The parameter table accepts writes only with Modbus function 22 to register 16386, as the template does; a function 16 write to the parameter table is not supported.

Available devices 6

These devices appear in TapHome after import.

Eliwell EWRC NT Module
Service Actions
Zapnúť zariadenie
Vypnúť zariadenie
Zapnúť úsporný režim
Vypnúť úsporný režim
Ručné rozmrazovanie
Potvrdenie alarmu

Eliwell EWRC NT

Read (module)
var alarmReg85 := MODBUSR(H, 33085, UInt16);
var alarmReg84 := MODBUSR(H, 33084, UInt16);
IF(GETBIT(alarmReg85, 5))
ADDERROR(0, "HA1: Prekročenie horného limitu teploty sondy 1");
END
IF(GETBIT(alarmReg85, 6))
ADDERROR(1, "LA1: Prekročenie dolného limitu teploty sondy 1");
END
IF(GETBIT(alarmReg85, 4))
ADDERROR(2, "EAL: Externý alarm");
END
IF(GETBIT(alarmReg85, 7))
ADDERROR(3, "OPd: Alarm — otvorené dvere");
END
IF(GETBIT(alarmReg85, 1))
ADDERROR(4, "E1: Chyba sondy 1");
END
IF(GETBIT(alarmReg85, 2))
ADDERROR(5, "E2: Chyba sondy 2");
END
IF(GETBIT(alarmReg84, 5))
ADDERROR(6, "E3: Chyba sondy 3");
END
IF(GETBIT(alarmReg84, 7))
ADDERROR(7, "PA: Alarm tlakového spínača");
END
IF(GETBIT(alarmReg84, 4))
ADDERROR(8, "ALd: Únik chladiva");
END
IF(GETBIT(alarmReg84, 6))
ADDERROR(9, "E10: Chyba hodín");
END
Service Actions
Zapnúť zariadenie
MODBUSW(H, 33057, UInt16, 64)
Vypnúť zariadenie
MODBUSW(H, 33057, UInt16, 128)
Zapnúť úsporný režim
MODBUSW(H, 33057, UInt16, 4)
Vypnúť úsporný režim
MODBUSW(H, 33057, UInt16, 8)
Ručné rozmrazovanie
MODBUSW(H, 33058, UInt16, 2)
Potvrdenie alarmu
MODBUSW(H, 33058, UInt16, 1)
Teplota – sonda 2 Temperature Sensor

Teplota – sonda 2

Read temperature
MODBUSR(H, 347, Int16) / 10
Stav zariadenia Switch
Values / States: Zapnuté · Vypnuté

Stav zariadenia

Read switch state
GETBIT(MODBUSR(H, 33089, UInt16), 1)
Read (module)
var stav := MODBUSR(H, 33089, UInt16);
var komp := MODBUSR(H, 33092, UInt16);
IF(GETBIT(stav, 0))
ADDINFO(0, "Úsporný režim aktívny");
END
IF(GETBIT(stav, 2))
ADDINFO(1, "Osvetlenie zapnuté");
END
IF(GETBIT(stav, 4))
ADDINFO(2, "Pomocný výstup aktívny");
END
IF(GETBIT(komp, 3))
ADDINFO(3, "Kompresor 1 beží");
END
IF(GETBIT(komp, 4))
ADDINFO(4, "Rozmrazovanie 1 aktívne");
END
Teplotný setpoint Thermostat

Teplotný setpoint

Read temperature
MODBUSR(H, 345, Int16) / 10
Read desired temperature
MODBUSR(A, 16386, Int16)
Write desired temperature
MODBUSWNE(A, 16386, Int16, Se)
Alarmný limit – maximum (HAL) Variable

Alarmný limit – maximum (HAL)

Read
MODBUSR(A, 16418, Int16) / 10
Write
MODBUSWNE(A, 16418, Int16, Va * 10)
Alarmný limit – minimum (LAL) Variable

Alarmný limit – minimum (LAL)

Read
MODBUSR(A, 16420, Int16) / 10
Write
MODBUSWNE(A, 16420, Int16, Va * 10)
Alarmný limit – minimum (LAL) Variable

Alarmný limit – minimum (LAL)

Read
MODBUSR(A, 16420, Int16) / 10
Write
MODBUSWNE(A, 16420, Int16, Va * 10)
Connection: Modbus RTU • 9600 baud• 8N1 • Slave ID: $[SlaveId]

Import parameters

Enter these values when you import the XML.

Asked in the appDefault
Modbus Slave ID1

Related Documentation

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Template · TapHome portal Eliwell EWRC 300/500/5000 NT Open this template in the Customer Portal to apply it to one of your homes, or to draft a refinement and submit it back to the catalog. Modbus RTU View in TapHome portal