Hello;

You should be able to use Mobus RTU easily through the CM 1241 RS-485 module. Of course you must understand the Modbus RTU parameters and mapping of your slave so you can read and write to the correct registers to control the ATV.

Just in case you do not have this document:

ATV312_Modbus_manual_EN_BBV52816_01.pdf

Implementation of the Modbus masterfunctionnality in the CM 1241implies that the CRC calculation has been taken care of in the code. The user does not have to generate any special code for this.

Here is a link to a detailed explanation of the Modbus functions to use on the S7-1200 (to command a CM 1241), including sample code that you can study and use in your program:

How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200?

Hope this helps,

Daniel Chartier

New question published by Xavi17 is split to a separate thread with the subject Communicate CM1241 RS485 with ATV312 RS485.

Best regards
Jen_Moderator