RSLogix PIDE SPOper being cleared when changing modes?

[daveman]

I have 2 PID loops controlling a valve, the primary one is controlled from flow, and the secondary one is controlled off pressure if the pressure rises above a setpoint.

I have them setup so that the one in control is in Operator Auto and the one not in control is in Program Manual and the active PID's CV is followed. However when I switch from Operator Auto to Program Manual, the PIDE SPOper Value is cleared to zero.

In Program Manual I also cannot adjust SPOper either in the logic or at the HMI. Ideally I want to set SPOper so that whenever the PID enters Program Auto, SPOper is persistent and will be the setpoint used.

I also want to be able to set SPOper when the PID is in Program Manual, as this affects the switchover point. Am I missing something? Thanks

 

[Ron Beaufort]

welcome to the forum ...

I recommend that you take a look at the FIRST TWO posts of the thread at the following link ...

http://forums.mrplc.com/index.php?showtopic=14562&view=findpost&p=71278

the information there has helped many people with questions similar to yours ... be sure to look at the PDF files which are attached to each post ... if that doesn't help, then I recommend that you post your entire program file here ... we'll be glad to take a look and try to help you nail all of this down ... (you'll have to zip the file before posting - forum rule) ...

good luck with your project ...

 

[jamesau]

In addition to Ron's suggestion, see also http://www.plctalk.net/qanda/showthread.php?t=68732

 

[John M]

The part on Multiloop Selection in the document that jamesau suggested is what you want. There is no need to put either of the loops in manual if you set it up this way.