Studio 5000 PID confusion/issue.

[g.mccormick]

PLC is a 1769-L30ER


PID instruction.

Setpoint = 26687
PV = 13537
Control Action = SP-PV.

Error should = 26687 - 13537 = 13150

Error listed as -836.45???


I can't figure out what is happening here. The PID seems to be calculating a bogus error. This is then driving the PID to not increase the command.... Any help?

 

[g.mccormick]

I figured it out but I don't know why. The scaling tab had max values lower than current SP value. I increased the max values to higher than what I'd expect to see for SP and the PID error is calculating correctly.