rta53
Lifetime Supporting Member
I normally do all the PLC programming for our small company but occasionally we have farmed out some of our programming. Attached (if it works) is 2 ways someone programmed analog outputs for a
Level Control Valve and a Pressure Control Valve. The 1st 2 rungs are for the LCV and the next rung shows what he did for the PCV. Is it possible to use a PID instruction as he did without rescaling the output?
Anyway, the LCV is working fine but the output to the PCV never seems to go above 10 mA or so even though the Control Output CV is showing 100% in the PID setup. I confirmed this by looking at the Output data file and O:16.3 is at 16383.
Should I use an SCP instruction and rescale the analog output to the PCV? The module I am using is a 1746-NO4I. According to the manual it looks like a 4-20mA module shouled be scaled 6242 to 31208. Is this correct?
For the LCV the guy used 0 to 32767 to scale the output.
I really don't want to get into why I don't ask the person who did the programming to explain. I need to fix this myself.
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Level Control Valve and a Pressure Control Valve. The 1st 2 rungs are for the LCV and the next rung shows what he did for the PCV. Is it possible to use a PID instruction as he did without rescaling the output?
Anyway, the LCV is working fine but the output to the PCV never seems to go above 10 mA or so even though the Control Output CV is showing 100% in the PID setup. I confirmed this by looking at the Output data file and O:16.3 is at 16383.
Should I use an SCP instruction and rescale the analog output to the PCV? The module I am using is a 1746-NO4I. According to the manual it looks like a 4-20mA module shouled be scaled 6242 to 31208. Is this correct?
For the LCV the guy used 0 to 32767 to scale the output.
I really don't want to get into why I don't ask the person who did the programming to explain. I need to fix this myself.
[attachment]