darkvader

Hello

I've a PID using FC41 ContC Block, built in CFC v 7.0.

The block run in OB35, and it's sample time is 0.1. I've changed it to 0.5, but thr behaviour still the same.

Even in Manual Mode, the LMN output, have some spikes down to zero, time to time (not with a constant period), and the comes again to the manual mode value, introduced by the operator.

What could be the cause of that?

Any help please?

Regards

DV

darkvader

Hellohdhosseini

Thank you for your advise.

In fact I'm using FB41 Cont_C, block (sorry, it was a type mistake in the Topic subject writing FC, instead of FB).

Till now I've downloaded to the PLC CPU the CFC witch contains the PID control block FB41, but didn't reset yet the PLC, because at that moment can't shutdown the production line.

In this PLC (S7-412-2DP),I've old software application built in FBD. Now I have the CFC tool integrated in Simatic Manager, and the new software applications are built using CFC.

In the old applications using FBD I usually put in OB100 a set bit instruction, to set to 1 the COM_RST FB41 CONT_C bit.

When the PLC restarts this instruction do a temporary (because is in the OB100) set to 1 of that bit, and the same to the others corresponding to other PID's I have in the application.

In the CFC, when I have a PID block like the PB41 Cont_C, I don't see were this kind of instruction is done, but I see in the Proprieties of that block, the checkmark in the "To be inserted in OB/tasks: COMPLETE RESTART (complete restart)", thais the OB100.