What are the available methods for M580 ModbusTCP/IP communication to a Modbus slave/server?


04 November 2021

Method 1 is IO scanning which can be set up through the DTM browser of Control Expert. The created Modbus variables will appear in the Device DDT Variables table.

Method 2 is explicit messaging which involves using Read_var, Write_var and/or Data_Exch function blocks in the program. Note Read_Var and Write_Var must be used in combination with the ADDM or ADDMX function block.

IO scanning (implicit messaging) can be done at the same time as Read_var and Write_var (explicit msg) to the same modbus slave and to the same registers. These can also be done simultaneously to different registers.