---
title: "Eliwell EWRC 300/500/5000 NT"
description: "Eliwell EWRC 300/500/5000 NT over Modbus RTU: probe temperatures, setpoint, alarm limits, alarms, defrost. Needs RS-485 module; set PtS = d, 9600 8N1."
url: "https://taphome.com/en/compatibility/eliwell-ewrc-300-500-5000-nt/"
language: en
lastmod: 2026-11-12
generator: hugo
ai:
  topics: ["modbus-rtu","rs485","refrigeration-controller","cold-room","temperature-controller","thermostat"]
  questions: ["How to integrate the Eliwell EWRC 300/500/5000 NT with TapHome?","What does the Eliwell EWRC NT TapHome template read and control?","How to connect the Eliwell EWRC NT to TapHome via Modbus RTU on RS-485?","How to enable Modbus on the Eliwell EWRC NT with parameter PtS?","Which parity, baud rate and address does the Eliwell EWRC NT use for Modbus?","Does the Eliwell EWRC NT need the optional RS-485 module for Modbus?","Why does the Eliwell EWRC NT not answer Modbus requests?","Can TapHome start a manual defrost or acknowledge alarms on the Eliwell EWRC NT?"]
---

# Eliwell EWRC 300/500/5000 NT

Communication: Modbus RTU

## 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.

> [!WARNING]
> 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](https://taphome.com/images/compatibility/eliwell-ewrc-300-500-5000-nt/wiring-terminals_hu_135d4b4c214f325c.jpg)

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.

> [!WARNING]
> 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.

| Parameter | Meaning | Values | Factory default | Register |
|-----------|---------|--------|-----------------|----------|
| `PtS` | Protocol of serial port COM1 | `t` = Televis, `d` = Modbus | `t` (MSK 554), `d` (MSK 812) | 49289 |
| `Adr` | Modbus address | 1–250 | 1 | 49422 |
| `Pty` | Modbus parity | `n` = none, `E` = even, `o` = odd | `n` (MSK 554), `E` (MSK 812) | 49292 |
| `StP` | Modbus stop bits | `1b`, `2b` | `1b` | 49293 |
| `bAU` | Baud rate | `96` = 9600, `192` = 19200, `384` = 38400 Bd | `96` | 49421 |

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](https://taphome.com/images/compatibility/eliwell-ewrc-300-500-5000-nt/modbus-settings_hu_c44ae13af4ec0df6.jpg)

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.

> [!WARNING]
> 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

| Device | What it does | Register | Access |
|--------|--------------|----------|--------|
| Thermostat | Cold room temperature (probe 1) and regulation setpoint `SEt` | 345 (temperature), 16386 (setpoint) | Read / write setpoint |
| Probe 2 temperature | Temperature of analogue input Pb2 | 347 | Read |
| Device state | Controller on/off with operating details | 33089, 33092 | Read |
| High alarm threshold (`HAL`) | Maximum temperature alarm limit | 16418 | Read / write |
| Low alarm threshold (`LAL`) | Minimum temperature alarm limit | 16420 | Read / 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):

| Code | Alarm |
|------|-------|
| HA1 | Probe 1 high temperature threshold exceeded |
| LA1 | Probe 1 low temperature threshold exceeded |
| EAL | External alarm |
| OPd | Door open |
| E1 | Probe 1 error |
| E2 | Probe 2 error |
| E3 | Probe 3 error |
| PA | Pressure switch alarm |
| ALd | Refrigerant leak |
| E10 | Clock error |

### Commands

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

| Action | Register | Value |
|--------|----------|-------|
| Device on | 33057 | 64 (bit 6) |
| Device off | 33057 | 128 (bit 7) |
| Economy mode on | 33057 | 4 (bit 2) |
| Economy mode off | 33057 | 8 (bit 3) |
| Manual defrost | 33058 | 2 (bit 1) |
| Alarm acknowledgement | 33058 | 1 (bit 0) |

> [!NOTE]
> 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    |

Read (module)

```taphome
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

```taphome
MODBUSW(H, 33057, UInt16, 64)
```

Vypnúť zariadenie

```taphome
MODBUSW(H, 33057, UInt16, 128)
```

Zapnúť úsporný režim

```taphome
MODBUSW(H, 33057, UInt16, 4)
```

Vypnúť úsporný režim

```taphome
MODBUSW(H, 33057, UInt16, 8)
```

Ručné rozmrazovanie

```taphome
MODBUSW(H, 33058, UInt16, 2)
```

Potvrdenie alarmu

```taphome
MODBUSW(H, 33058, UInt16, 1)
```

Teplota – sonda 2 Temperature Sensor

Read temperature

```taphome
MODBUSR(H, 347, Int16) / 10
```

Stav zariadenia Switch

Values / States: Zapnuté · Vypnuté

Read switch state

```taphome
GETBIT(MODBUSR(H, 33089, UInt16), 1)
```

Read (module)

```taphome
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

Read temperature

```taphome
MODBUSR(H, 345, Int16) / 10
```

Read desired temperature

```taphome
MODBUSR(A, 16386, Int16)
```

Write desired temperature

```taphome
MODBUSWNE(A, 16386, Int16, Se)
```

Alarmný limit – maximum (HAL) Variable

Read

```taphome
MODBUSR(A, 16418, Int16) / 10
```

Write

```taphome
MODBUSWNE(A, 16418, Int16, Va * 10)
```

Alarmný limit – minimum (LAL) Variable

Read

```taphome
MODBUSR(A, 16420, Int16) / 10
```

Write

```taphome
MODBUSWNE(A, 16420, Int16, Va * 10)
```

Alarmný limit – minimum (LAL) Variable

Read

```taphome
MODBUSR(A, 16420, Int16) / 10
```

Write

```taphome
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 app | Default |
|------------------|---------|
| Modbus Slave ID  | `1`     |

## Related Documentation

- [Modbus Integration](https://taphome.com/en/compatibility/modbus-guide/)
- [Modbus](https://taphome.com/en/docs/integration/modbus/)
- [Simple configuration using templates](https://taphome.com/en/docs/integration/modbus/templates/)
- [Modbus scripts and prefetch](https://taphome.com/en/docs/script/modbus-scripts/)
- [Modbus functions](https://taphome.com/en/docs/script/modbus/)
- [Modbus data types](https://taphome.com/en/docs/script/modbus-data-types/)