Studio 5000 PID.

[Dale87]

I'm setting up a PID for a 50hp RO pump in a water treatment plant. When I go to manual mode on hmi I set the swm bit, I also ons the pid output% to the hmi manual input% so there's no bumps. How can I do it the other way? When I switch from manual to auto it ignores the value I had in manual and goes back to the pid output. I want the pid to take over at the manual output% and adjust from there.

 

[glennz]

Are you using .SO for your bumpless transfer value? From the manual:

"Software manual (.SWM):

This mode is also known as set output mode and allows the user to set the output % from the software. The set output (.SO) value is used as the output of the loop. The set output value typically comes from an operator input from an operator interface device."

I think you can also use the so-called 'tieback' value the same way, in conjunction with .MO. See Publication 1756-RM003Y-EN-P, page 624.

 

[Dale87]

Thank you. I was using a move instruction after the SWM xic bit to the analog output, just bypassing the PID. But was running into problems. Now when in manual (swm) I'm moving my hmi speed value to the SO register.

 

[drbitboy]

So now it looks something like this?

 

[Dale87]

Pretty close

 

[ASF]

Also turn on PV Tracking (.PVT) when you switch to Software Manual