PID in Lookout 5.0

[Billy_d]

I have a client having problems with 3 PID loops in Lookout 5.
I have tried to help tune one of them over the phone without success. (The others are not operational).

Foxboro Mag Flow meter.
Liquid: Brine.
Span: 0 to 200 USGPM, Gain: 0.18, Reset::0.01 and Rate: 0
Sample Pulse timer: duration: 0.1s, period: 0.5s
I/O is Fieldpoint, 4-20mA modules for both input and output.
Connection is by RS232 at 115.2K to a local PC.
Poll rate: 0.5 sec
Total I/O count is 12 according to the Lookout help box.

The gain works as expected (with gain only the control is offset (proportional offset)), however adding reset does not bring the process back to the setpoint. Instead it transtitions from having no effect to sudden wild oscillation.

Over the phone it's difficult to know what is going wrong (they are a thousand miles away). They say their valve is operating correctly (no sticking etc), so I wondered if it was something to do with the way I have set up the pid object in Lookout.
Any help appreciated!

[Ryan.S]

The configuration of gain, reset and rate might not be proper.

Try to increase the reset value.

[Billy_d]

Hi Ryan,
Rate is set at zero so it has no effect. (P+I should work well in this flow loop).
Gain (0.18) is half the amount at which incipient oscillation occurs.
As I mentioned, reducing the reset does nothing unil a critical "breakpoint" at which the flow goes into wild oscillation.
In other words, increasing the reset from 0.01 has no effect on the process, but decreasing it to (say) 0.009 causes oscillation.

Reset in Lookout is minutes per repeat isn't it?
Regards,
Bill