I'm getting alergic reaction talking about serial communication :( Can it be so unstable???

I'm using CP441-2 for Modbus RTU communication and have again a dropdown in communication. Previously I had it much often, but I programed a delayed communication startup after PLC Startup, and may be that helped.

But now a problem again, I just reconnected the PowerSupply cable to the Modbus slave modules (they went down of course) but when I restored the PS the communication is not working any more :(

I tried with PLC Stop-Start but it didn't work. Now I'll went for factory to stopp and then I can Power down as you mentioned here an chech if that will help.

If I get the communication running tomorrow this will be unbelievable - I'll be happy but at the same time very confused, is't it really any way to restore a communication when it drops down for some reason ??? 

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Split from FB12 BSEND ERROR CODE 2.

Hi, Kaulquappe!

I'm having problems with CP441-2 running Modbus RTU Master on RS485.

Last week I powered down all the slaves just to rearange the power supply wire for the Modbus an then I lost all communication. The SFB12 (BSEND) returned just fails and couldn't start communication again. Even the green lights on the CP didn't light on on send/receive. The call of SFB12 returned error 2 or 19 all the time, I stop/start the PLC but that didn't help. 

Today I powered off the Power supply, and then started again, than the CP started communicating again. 

Basicly I'm calling SFB12 every PLC cycle if Error or Done flag appears I went for another cycle before trigger new BSEND_REQ. As long there is an Error I don't read by SFB13 (BRECV).

But after this last eror ot was jsut Power reset which fikset the communication.

Is there other ways to reset the CP441-2 so I don't need to reset the whole PLC.?