To send and receive data on Master side we need to use 2 channels:

  • TO RECEIVE DATA - Read Input Registers (Function Code 04)
  • TO SEND DATA - Write Multiple Registers (Function Code 16)

Step 1. Modbus Slave Channel - Add channel - FC 04 - Length 10

To get or read data we need to use channel 0 with access type Read Input Registers (Function Code 04).

Since we have decided to use approximately 8 variables, the length will be set to 10 (this value can be changed).

Step 2. Modbus Slave Channel - Add channel - FC 16 - Length 10

To sent or write data we need to use channel 1 with access type Write Multiple Registers (Function Code 16)

Since we have decided to use approximately 8 variables, the length will be set to 10 (this value can be changed).

NB!

As a result:

Step3. ModbusTCP Slave I/O Mapping - Enabled 2 (always in bus cycle task)

Step4. In this step we need to define our variables.

NB! The register 0 we have for BOOL variables. 

En example for Reading registers - INPUT

En example for Writing registers - OUTPUT


Now we need to map the server/slave side

Sending and receiving of data on the Server/Slave side

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