M340 Modbus Scanner

[ryanAstiefes]

I've done some digging and cannot find any documentation for a Modbus RTU scanner using an M340 PLC. Can someone point me in the right direction. Thanks

[AlastairF]

Are you working in Automation Expert/ IEC61499 environment or Control Expert/ IEC61131 environment?
M340 is not supported as a dPAC in Automation Expert.

Under Control Expert, M340 ModBus RTU support is via the serial port on selected CPU's or via the BMXNOM0200 serial module.

In both hardware cases you need to configure the selected port physical characteristics and then use the READ_VAR or WRITE_VAR command for the communications. You can also use the DATA_EXCH command.

[ryanAstiefes]

Thanks for the reply. I understand the ReadVar & WriteVar commands, which need setup to systematically be called on one at a time. I am referring to a scanner which will automatically scan my registers I program in. Just like an I/O scanner. Is this even available on the M340 using Control Expert. 

[AlastairF]

I would suggest using the 2022 Modicon Libraries for Control Expert.

There are communication scheduling functions in there that should work to achieve what you are looking for.

Communication blocks are available to work with Serial and Ethernet connections

https://www.se.com/ww/en/download/document/GPLECE2022/

Have a read of the Communications manual first.