---
title: "ComWinTop CWT-THxxx"
description: "Monitor temperature and humidity via Modbus RTU with ComWinTop CWT-THxxS sensors. Configurable slave ID and baud rate, RS-485 up to 800m. TapHome integration template."
url: "https://taphome.com/en/compatibility/comwintop-cwt-thxxx/"
language: en
lastmod: 2026-03-29
generator: hugo
ai:
  topics: ["modbus-rtu","sensor","rs485","temperature","humidity"]
  questions: ["How to integrate ComWinTop CWT-THxxx with TapHome?","What does the ComWinTop CWT-THxxx TapHome template measure?","How to connect ComWinTop CWT-THxxx via RS-485 to TapHome?","How to change the slave ID on ComWinTop CWT-THxxx?","What is the default baud rate for ComWinTop CWT-THxxx sensors?"]
---

# ComWinTop CWT-THxxx

Communication: Modbus RTU

- [ComWinTop CWT-THxxS Product Page](https://store.comwintop.com/products/rs485-modbus-water-proof-temperature-humidity-sensor-probe)

## Integration guide

The ComWinTop CWT-THxxx series are RS-485 Modbus RTU temperature and humidity sensors available in multiple probe form factors (CWT-TH01S through CWT-TH05S). The TapHome template reads temperature and relative humidity values and provides service actions for configuring the slave ID and baud rate directly from TapHome.

The sensors are powered by DC 5–30 V and communicate over RS-485 at distances up to 800 m, making them suitable for distributed building monitoring.

## Hardware connection

### Wiring

The sensor has a 4-wire cable:

| Cable Color | Function |
|-------------|----------|
| Brown | Power + (DC 5–30 V) |
| Black | Power − (GND) |
| Yellow / Green | RS-485 A+ |
| Blue | RS-485 B− |

Connect the RS-485 A+ and B− wires to the corresponding terminals on a TapHome Modbus RTU gateway (e.g. TapHome Core RS-485 bus). The power GND and RS-485 GND should share a common ground.

> [!WARNING]
> Ensure proper grounding between the sensor and the Modbus gateway. Without a shared GND reference, communication errors are likely, especially on longer cable runs.

### Specifications

| Parameter | Value |
|-----------|-------|
| Power supply | DC 5–30 V, < 0.1 W |
| Temperature range | −30°C to +80°C (±0.5°C) |
| Humidity range | 0–100% RH (±5% RH) |
| Resolution | 0.1°C / 0.1% RH |
| Communication | RS-485 Modbus RTU |
| Max cable length | 800 m |

## Configuration

### Communication parameters

The TapHome template uses **9600 baud, 8 data bits, no parity, 1 stop bit**. The factory default baud rate is 4800 bps — use the **Set Baud Rate** service action in TapHome (or a Modbus tool) to change it to 9600 before importing the template.

Alternatively, if you prefer to keep the factory 4800 baud rate, adjust the baud rate in the TapHome module connection settings after import.

### Slave ID

The default slave ID is **1**. When connecting multiple CWT-THxxx sensors on the same RS-485 bus, each sensor needs a unique slave ID (1–254). Use the **Set Slave ID** service action in TapHome to change the address.

## Device capabilities

### Temperature and humidity monitoring

The template exposes a single **Temperature & Humidity Sensor** device that reads:

- **Temperature** — ambient temperature in °C (register H:1, Int16, ÷10 conversion). Range −30°C to +80°C with 0.1°C resolution. Negative temperatures use two's complement encoding.
- **Humidity** — relative humidity in %RH (register H:0, UInt16, ÷1000 conversion). Range 0–100% RH with 0.1% resolution.

### Service diagnostics and configuration

The module provides two service attributes and two service actions for bus configuration:

- **Slave ID** (read from H:2000) — displays the current Modbus address
- **Baud Rate** (read from H:2001) — displays the current baud rate (2400, 4800, or 9600)
- **Set Slave ID** — writes a new address (1–254) to H:2000
- **Set Baud Rate** — writes a new baud rate selection to H:2001 (0 = 2400, 1 = 4800, 2 = 9600)

### Additional capabilities

The CWT-THxxx sensors also provide calibration registers for temperature offset (H:0x0050) and humidity offset (H:0x0051) with 0.1°C / 0.1% RH resolution. These allow fine-tuning measurements without modifying the TapHome configuration. Calibration support can be added in a future template update.

## Troubleshooting

### No readings after import

1. Verify the baud rate matches between the sensor and TapHome — the template expects 9600 bps but the factory default is 4800
2. Check the RS-485 wiring: A+ to A+, B− to B−, shared GND
3. Confirm the correct slave ID is set in the TapHome import parameters

### Incorrect humidity values

The template uses a ÷1000 scale factor for the humidity register, as defined in the XML template. If readings appear off by a factor of 100, this may indicate a firmware variation. The XML template is the authoritative source for the TapHome integration.

### Communication errors on long cable runs

1. Ensure a shared GND connection between the sensor and the gateway
2. Use twisted-pair cable for the A+/B− lines
3. Add a 120 Ω termination resistor at the end of the bus if the cable exceeds 100 m

## Available devices 1

These devices appear in TapHome after import.

ComWinTop CWT-THxxx Module

Service Attributes

|           |                                                       |
|-----------|-------------------------------------------------------|
| Slave ID  |                                                       |
| Baud Rate | Current communication speed — 2400, 4800, or 9600 bps |

Service Actions

|               |                                                                              |
|---------------|------------------------------------------------------------------------------|
| Set Slave ID  | Changes the Modbus slave address (1–254) for multi-sensor bus configurations |
| Set Baud Rate | Changes the communication speed — 2400, 4800, or 9600 bps                    |

Service Attributes

Slave ID

```taphome
modbusr(H, 2000, Uint16)
```

Baud Rate

```taphome
switch( modbusr(H, 2001, Uint16),
0, "2400",
1, "4800",
2, "9600",
"Unknown")
```

Service Actions

Set Slave ID

Parameters: ID (1–254 ID)

```taphome
modbusw(H, 2000, Uint16, ID)
```

Set Baud Rate

Parameters: Baud Rate

```taphome
modbusw(H, 2001, Uint16, bps)
```

Temperature & Humidity Sensor Temperature Sensor Read-only

Ambient temperature (°C) and relative humidity (%RH) with automatic unit conversion

Register: H:1 Int16 Unit: °C numeric

Read humidity

```taphome
MODBUSR(H, 0, Uint16) / 1000
```

Read temperature

```taphome
MODBUSR(H, 1, Int16) / 10
```

**Connection:** Modbus RTU • 9600 baud• 8N1 • Slave ID: $\[SlaveId]

Possible improvements (2)

- H:0x0050 Temperature Calibration — Int16 R/W, 0.1°C resolution offset adjustment for fine-tuning temperature readings
- H:0x0051 Humidity Calibration — UInt16 R/W, 0.1% RH resolution offset adjustment for fine-tuning humidity readings

## Import parameters

Enter these values when you import the XML.

| Asked in the app | Default       |
|------------------|---------------|
| Slave Id         | `1`           |
| IP address       | `192.168.1.0` |

## Sources

- ComWinTop CWT-THxxS Product Page — Specs & Modbus Protocol
  
  [store.comwintop.com](https://store.comwintop.com/products/rs485-modbus-water-proof-temperature-humidity-sensor-probe) 2026-03-29
- Home Assistant Community — CWT Modbus RTU Configuration
  
  [community.home-assistant.io](https://community.home-assistant.io/t/config-for-rtu-modbus-temperature-sensor/732447) 2026-03-29

## 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/)