Hi,

I have a 1214C v3.0 CPU with a CM1241 v2.0 rs-485 communication module.

s7-1200 is a modbus master retrieving data from a temperature sensor network (1-wire to rs-485 interface), two electrical consumption meters and one heat meter. Total four slave devices.

Everything works fine but the CM1241 crashes randomly, sometimes after one day sometimes after two months. When it is failing the Tx and Rx lights are not blinking anymore and the only way to restart is to shut cpu power for a couple of seconds or switch the cpu from run to stop and back. After that everything is normal again.

i use one mb_comm_load to setup baud rate and stop bits on first cycle and four mb_master commands executed in sequence to retrieve the data from the different units. The mb_master sequence is restarted every fourth second.

all ideas are welcome

best regards

Fredrik

HelloFredrik567

Firstly Like these Problems you should check your Cables sockets , Measurement the Signals should be about 10.8 to 12 V if you are using RS485 communications.

Second Check the distance of your communication.

Third Check your Boud rate and check if your distance is suitable to it.

I am running 19200 baud and total cable length from cm1241 to last slave in the chain is about 15 metres.

 Cable is standard cat5e networking cable.

regarding signal voltage I have to come back later.

br

Fredrik

William_B

 

Fredrik567

I am running 19600 baud and total cable length from cm1241 to last slave in the chain is about 15 metres.

 Cable is standard cat5e networking cable.

regarding signal voltage I have to come back later.

br

Fredrik

The baud is 9,600 or 19,200 .. surely not 19,600.
Maybe the time-out setting needs to be set higher?

sorry for that, I have corrected my last post to 19200 baud.

time-out setting? Is it found under CM1241 properties?

br

Fredrik

Fredrik567

 

sorry for that, I have corrected my last post to 19200 baud.

time-out setting? Is it found under CM1241 properties?

br

Fredrik

 

 yes. change time out to about 1000 ms.

Thanks for your answers. I am trying with higher time out setting now.

As my errors are very random I will need some weeks to evaluate!

Fredrik567

Thanks for your answers. I am trying with higher time out setting now.

As my errors are very random I will need some weeks to evaluate!

 Hi Fredrik567

How about your crash problem. Do you have resolved it ?

I had it now, the same problem with you. Sometime the module CM1241 RS-485 with Modbus Master block is crashed, no yellow led comunication blinking and no data get. If I restart the CPU , it OK again but sometime still crash. I have checked connection, baudrate, cable.

If you resolved your problem, please so me how to do.

Thank you !