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General => Technical support => Topic started by: MarkWater on June 03, 2014, 02:51:57 PM

Title: Pausing PID
Post by: MarkWater on June 03, 2014, 02:51:57 PM

Hello All,

I'm running a PID loop on a FMD8810, it works great. I am using a flow meter to control an automated valve which varies flow until my setpoint is achieved. Under certain conditions in order to achieve the setpoint the valve allows the line to be over pressurized. I am already reading this line presssure through a transducer. Is there a simple way to pause the PID loop at pressure X and then resume after once the pressure drops below x?

Title: Re:Pausing PID
Post by: support on June 03, 2014, 03:20:41 PM

The PID loop would have been called by your program periodically (e.g. using a clock pulse)? If so then all you need to do is to sample the ADC input at the beginning of the custom function that contains the PIDcompute and if it rises above certain value you can simply execute a RETURN and skip the rest of the function where PIDcompute is used to control the output.