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P1000 PID Ramp/Soak

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  • P1000 PID Ramp/Soak

    I have a PID set up for a brewing system. I added a ramp/soak profile to allow the user to step the temp setting automatically during the process. The ramp time is set to zero, the set point is set by the user and copied into the PID set point location when the ramp/soak is enabled. The soak time is user entered. I have the time base set up to minutes. The issue that i am having is that once the temp hits the set point in step 1 it does not soak for the user entered time. It will just advance to step number two without soaking for the entered time. All my number values are in 32 bit integers. I am not sure why the set point is not holding.

  • #2
    Is the soak time being sent to the ramp/soak instruction when the user has entered it? can you see it being updated in the data view or instruction in monitor mode?
    Is the ramp/soak instruction enabled before the soak time is sent to the instruction?
    I wouldn't think the 0 ramp time would have anything to do with it, but if you change it to something like 1 second, does it still do this?


    • #3
      the set point is set by the user and copied into the PID set point location when the ramp/soak is enabled.
      If the ramp time is equal to 0 then when the ramp/soak is "enabled" and put into "run" the soak time will begin. It will not wait on your PV of your process to get to that setpoint before starting the soak. In order to do what you are trying to you would have to include feedback from your process variable.

      Here is a line of code that would load the first SP when ramp soak was enabled and then put the ramp/soak in run only after each sp is reached by the pv to soak before loading the next sp to your process. (temp would be your process variable temperature from your process)

      Click image for larger version

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      • #4
        Thank you. Would I have to write this for each step temp. I will have up to 5 in the ramp soak. Could I set this up as a task to be called when a switch is on form the touchscreen. Or is this line of code for all of the 5 steps??