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Hi,

First time I am using PID on a Jazz.

I want to keep the pressure within a system steady, regulated by a solenoid valve that has a constant pressure supply on it; and in turn feeds the closed system. 

Attached are my setup and I have a few questions:

1. My CV is the controlled digital output on the solenoid valve that opens when the pressure drops; reads of a 0-10V pressure sensor; and closes when that pressure reaches my setpoint.  How can I setup the CV to a digital output?

2. My Process Value and Setpoint I have them linked to the same MI because I want to keep the pressure at whatever pressure the pressure sensor reads from the beginning. Is that correct to do?

3. I cant seem to make it to operate the solenoid valve because I don't understand what the Control Value MI should be in order to simulate a digital output. I also set its range 0 and 1 but it needs further processing

 

Thanks

PID Setup.PNG

PIDSetupLadder.PNG

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You change the value in the CV output to a digital output using PWM.  Check the Help on that and then post your program with any questions.

Also, look at the Help on "power-up".  You can set the value of and MI when the PLC powers up - you don't need all those Store blocks.

Joe T.

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Thanks Joe for the input.

So I set up the PWM Output as follows and set my numbers to the SI for the PID. 

As it is set up now once it reads a pressure drop of less than 30 it uses that number as a setpoint.

Something does not trigger the PWM output

HardwareConfig.PNG

PID LadderA.PNG

PIDSetup.PNG

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Hi Joe,

I dropped the PID in favor to on/off control. Turned out to be much simpler in my application. Also I figured out how to trigger the PWM output with 100% of the cycle time.

Thanks for the help

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