How to use the xxmit block? Do you have any idea?
Just apply the xxmit function block to communicate with my RS232-485 converter? Should I use other blocks to communicate?

Thanks in advance...

 

I have been using this function in a lot of different cases and places, and I think I can help you. It's enough to use the XXMIT function to read data, but you have to set correctly all the parameters:

Command: 2100H for RS485 or 100H for RS232
Message lendth: Usually 5
Port: The number of the Port you are using
Baudrate: 9600, 19200, etc
Databits: Usually 8
Stopbits: Usually 1
Parity: Usually 2
Response tout: 1000
Retry Lmt:3
Startdly:100
Enddly:600

For message out you need an array [1..12] where you only use the 5 first elements, and they are:

Message[1]: Operation code :3 read registers
Message[2]: Number of registers that you read
Message[3]: Modbus address of the slave that you read
Message[4]: Address where you read (slave)
Message[5]: Address where you place the data (master)