■Explanation
This is a sample program of Modbus/TCP master.
Modbus/TCP communication can be executed by specifying the IP address and communication port.
■Execution example
For python
python3.10 tcpmaster.py
For gcc
./tcpmaster
■Screen Image
■Step to Use
1. Enter "0" and press the enter key.
2. In Init, enter the IP address of the device you want to access and the port number to use, and press the enter key to connect with the device.
3. To input or output via Modbus communication,
please click the button after setting the parameters of each function
code.
* Please refer to the following for the function
code corresponding to each button.
Function Code |
Function Name |
|---|---|
ReadCoils (FC 1) |
modbus_read_bits |
ReadDiscreteInputs (FC 2) |
modbus_read_input_bits |
ReadHoldingRegisters (FC 3) |
modbus_read_registers |
ReadInputRegisters (FC 4) |
modbus_read_input_registers |
WriteCoil (FC 5) |
modbus_write_bit |
WriteRegister (FC6) |
modbus_write_register |
WriteMultipleCoils (FC15) |
modbus_write_bits |
WriteMultipleRegisters (FC16) |
modbus_write_regsiters |
Data format for sending and receiving is as follows.
- Send Data (Hex)
Example) 01 0D AD
- Receive Data (Hex)
Example) 01 0D AD
- Send Data (Bin)
Example) 0 1 1
- Receive Data (Bin)
Example) 0 1 1
In this sample, the maximum number of reading is 2000 bits / 125 words,and
the maximum number of writing is 1968 bits / 123 words.
* This is the maximum value of the Modbus specifications.
4. To exit, enter "9" and press the Enter key.