Quote for a PID program

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1

Hi,

I need assistance on writing a program to control a fluid valve. I can some write simple code but this is a bit out of my league.

Basically the code will consist of:

1 analog potentiometer input for main control

1 analog sensor input to monitor the fluid pressure

1 pot to set the pressure limit

1 Analog output to control the device

The input pot is what controls the flow valve position at a 1:1 ratio, so the analog output value must follow the input value(closing the valve) until the pressure builds to the set limit of pressure pot and maintain that precise pressure until the main input falls low enough to where the pressure drops under the set limit and back to 1:1 ratio.

Anyone interested that has an idea on what I'm trying to achieve please contact me with a price to help me with this project. :slight_smile:

2

Hi,
As you've described this, it isn't a PID controller. You have an input-follower: valve output proportionally matches setpoint input, and a limiter: don't allow limit to exceed a certain point. If this is what you're looking for it should be pretty straightforward.

3

the analog output must follow the input unless the pressure builds too high then the PID will take control

That shows a complete misunderstanding of PID. PID will be in control ALL the time.

4

I'm sorry if I misrepresented what I am trying to accomplish. I thought that PID was needed anytime you must control the position of something. I suppose quickly turning on and off the output pin will accomplish the same thing.

Thanks