1. Introduction
The ComWinTop CWT-TM-8PT is an 8-channel temperature acquisition module designed for industrial applications. It supports PT100 and PT1000 RTD sensors and communicates via RS485 using the Modbus RTU protocol. This manual provides essential information for the proper installation, operation, and maintenance of the module.
Figure 1: Front view of the CWT-TM-8PT Module, showing terminal blocks and labels.
Video 1: Product overview of the CWT-TM-8PT module.
2. Setup
2.1. Physical Installation
The CWT-TM-8PT module is designed for 35mm DIN-rail mounting.
Figure 2: Bottom view showing the red DIN-rail mounting clips.
Figure 3: Side view of the module, highlighting ventilation slots.
2.2. Power Supply
The module requires a DC power supply within the range of 8V to 30V.
2.3. Terminal Connections
Refer to the table below for detailed terminal descriptions:
Figure 4: Terminal description table.
2.4. PT100/PT1000 Sensor Wiring
The module supports both two-wire and three-wire connections for PT100/PT1000 sensors. Ensure correct wiring as shown in the diagrams below.
Figure 5: PT100/PT1000 wiring diagrams. For two-wire connections, short RTD(n)- and GND.
3. Operating Instructions
3.1. RS485 Modbus RTU Communication
The module communicates using the Modbus RTU protocol over RS485. The default communication parameters are:
- Baud Rate: 9600 bps
- Parity: None (n)
- Data Bits: 8
- Stop Bits: 1
- Default Device Address: 1
3.2. Modbus Register Maps
The module uses specific Modbus registers for configuration and data acquisition.
3.2.1. Parameter Register Map (Function Code: 03H Read, 06H Write)
Figure 6: Modbus parameter register map for communication settings and device address.
3.2.2. Data Register Map (Function Code: 03H Read)
Figure 7: Modbus data register map for reading temperature values from channels.
3.3. Configuration Tool
A dedicated configuration tool is provided to simplify the setup and testing of the module. This tool allows you to set communication parameters, device address, and read sensor data.
Figure 8: Screenshot of the module's configuration tool interface.
4. Maintenance
The CWT-TM-8PT module is designed for robust operation with minimal maintenance. To ensure optimal performance:
- Keep the module clean and free from dust and debris.
- Periodically check all wiring connections for tightness and integrity.
- Ensure the operating environment remains within specified temperature and humidity ranges.
5. Troubleshooting
- Module not responding after changing ID: If the module stops responding after changing its Modbus ID, ensure the new ID is valid (1-250) and that your communication software is configured to use the new ID. If issues persist, try resetting the module if a reset procedure is available (refer to the PDF manual if provided) or contact support.
- Communication issues: Verify RS485 wiring (A to A, B to B). Ensure a 120-ohm termination resistor is added to both ends of the RS485 bus, as the module does not have one built-in. Check baud rate, parity, and stop bits match the module's settings.
- Incorrect temperature readings: Double-check PT100/PT1000 sensor wiring. For two-wire connections, ensure RTD- is properly shorted to the nearest GND pin. Verify sensor type (PT100 or PT1000) matches module configuration.
- No power: Check power supply connections and ensure voltage is within the 8V-30V DC range.
6. Specifications
Figure 9: Basic parameters and specifications of the CWT-TM-8PT module.
6.1. Dimensions
Figure 10: Physical dimensions: 14.5cm (L) x 8.9cm (W) x 4cm (H).
7. User Tips
- Termination Resistor: Always add a 120-ohm termination resistor at both ends of your RS485 bus, as this module does not have one built-in. This is crucial for stable communication.
- Wiring RTD-: For two-wire PT100/PT1000 connections, ensure the RTD- terminal is connected to the nearest GND pin for accurate readings.
- Software Tool: For scanning and configuration, tools like OpenModScan can be very versatile and helpful.
- PDF Manual: A detailed user manual in PDF format may be available for further reference. Please check the product page or contact the seller for the PDF document: User Manual (PDF).
8. Warranty and Support
For warranty information, technical support, or any issues not covered in this manual, please contact the seller directly. Provide your order details and a clear description of the problem for efficient assistance.