Hello dear experts,

Unsuccessfully I have been trying to establish a Modbus RTU communication from an S7 1200 with CB1241 RS485 to a Sentron 3WL COM16 communication module. I have read almost all topics and saw most likely all possible documentation available but I am missing something i guess as it doesn't work.

Using the PowerConfig software for 3WL ACB and properly configure the comm. interface ( Modbus in this case) on "go online" I can establish the communication, but from the CPU cannot (the diagnose LED of COM16 is red.) 

Does anybody have any idea?  I am using TIA Portal V14 SP1. Do i need the HSP for Sentron..or...?

To this extend this is the configuration:

CPU 1215C DC/DC/Rly / 6ES7 215-1HG40-0XB0 / V4.2

CB 1241 (RS485) 6ES7 241-1CH30-1XB0 / V1.0

COM16 Communication module : 3WL9111-1AT15-0AA0

Thanks in advance!

Hi bogdanbv,

Could you please send some screenshot with your configuratio  (Modbus RTU blocks programmed, etc...)

I assume your PLC has MASTER role, then you should use MB_MASTER function block. If so, is there any information at its STATUS output?

Br,

Cocolino

Hello,

Thanks for replying. I have no error on status words neither for comm load or for master.

I am attaching you the master block.

Hi,

Depending on the application, the information at the "STATUS" parameter is only available for the duration of one cycle. Since the CPUs work in the millisecond range, the information cannot always be noticed by the user. Maybe you are not seeing STATUS values because of that.

I suggest you to follow the following FAQ in order to be able to see real values of STATUS parameter.

https://support.industry.siemens.com/cs/ww/en/view/109745539

By the way, to my knowledge, is not a "good practice" to set clock marks to MB_MASTER REQ input.

For test it, at the beggining, i would do request manually.

Hope it helps.

Br,

Cocolino