1. Overview
The Kunlun Tongtai MCGS TPC series HMI touch panels support Modbus RTU master communication. This article explains in detail the Modbus RTU connection and configuration between an MCGS touch panel and a PLC.
2. Hardware Connection
- HMI COM port → RS485 converter → PLC RS485 port
- Wiring: connect A+ to A+ and B- to B-
- Pay attention to the termination resistor (required over long distances)
3. Configuration Software Setup
3.1 Create a New Device Connection
- Open the MCGS configuration software
- Add a device in the device window
- Select "Generic Serial Parent Device"
- Set the communication parameters: baud rate, data bits, parity, and stop bits
- Add a "Modbus RTU" device
- Set the slave address
3.2 Variable Connection
| Variable Type | Modbus Address | Function Code | Description |
|---|---|---|---|
| Digital (bit) | 0xxxx | 01/05/15 | Coils |
| Digital input | 1xxxx | 02 | Discrete inputs |
| Numeric (analog) | 4xxxx | 03/06/16 | Holding registers |
4. FAQ and Troubleshooting
- Check whether the communication parameters match those of the PLC
- Confirm that the slave address is set correctly
- Check whether the variable address format is correct
- Pay attention to the data type (16-bit/32-bit, signed/unsigned)
5. Summary
Key points for Modbus RTU communication on an MCGS touch panel:
- Add a Generic Serial Parent Device plus a Modbus RTU sub-device
- Set the correct communication parameters and slave address
- Enter variable addresses in Modbus format
- Pay attention to the data type and byte order
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