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Old November 3rd, 2017, 03:12 PM   #16
Clutchbone
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If I force it, it works but with no regulation of temperature; so the question remains how do I get this card to output? Did I set it up wrong? I think it is in the PID profile but I am not sure of any of this now.
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Old November 3rd, 2017, 03:24 PM   #17
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Delete your rung 18 which has an OUT to Platen Heat 1:1

Delete the 'Less Than' in the enable line of your PID. It should always function.

Change the following parameters in the PID:

Process Output - Platen Heat 1
Output Range Max - 4095
Output Range Min - 819
Output Upper Limit - 4095

This will try to adjust to measured temperature but probably will be either very wild or very sluggish. You'll have to work on tuning (adjusting the Gain, Reset and Rate) the PID loop for best control. Maybe use 'PID Tuning' under 'Tools'
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Last edited by bernie_carlton; November 3rd, 2017 at 03:26 PM.
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Old November 3rd, 2017, 03:31 PM   #18
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Delete rung 16, you are writing a 1 to your PID set point. You need to have something writing a proper value to the PID set point, like maybe an analog input scaled to maybe temperature values or similar.
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Old November 3rd, 2017, 03:52 PM   #19
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Clutchbone - successful use of the PID instruction requires that you have some basic knowledge of the action of a PID loop and the parameters which control it. If the concept of a PID loop (it is internal to the stand alone controllers you mentioned) is new to you I suggest you do some research.

Your rung 18, which we advised you to delete, is a crude attempt at temperature control.

If you used just it, without the PID rung, you could have had a MATH block at the end to move some value into Platen Heat 1. This value would have to be enough to raise the temperature to the setpoint. Actually it would probably be better if it was a bit higher than that.

You would also would have needed a rung which, if the temperature was greater than the setpoint to trigger a math block to move a lower number, even 0, into Platen Heat 1.

This would provide a very crude control of the temperature much like your basic home temperature control thermostat.

A PID attempts to provide a much more controlled response which ends up maintaining the temperature very precisely at the setpoint.

Imagine controlling the temperature yourself, watching the readout from the thermocouple and adjusting a potentiometer to vary the amount of heat from the heater. After a while you would find yourself developing strategies like 'full on' at the start but slowly tapering off the control as the temperature approached the setpoint to prevent overshoot. You might find yourself tweaking the potentiometer slightly from time to time if the temperature drifted from the setpoint. These are the type of things the PID loop does if properly tuned.
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Last edited by bernie_carlton; November 3rd, 2017 at 04:07 PM.
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Old November 3rd, 2017, 03:53 PM   #20
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I killed rung 16 and rung 18 a ways back due to the suggestions coming in. I did reset the values for the output. the only difference so far is now in data view I get a value of 0 instead of a 1.LamPress1.zip
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Old November 3rd, 2017, 04:23 PM   #21
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Remove the Less Than test, make sure Heat Bit is on.

What is the value in Set Temp Platen 1?

If you do have a proper value then slowly raise the value in Gain.
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Last edited by bernie_carlton; November 3rd, 2017 at 04:49 PM.
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Old November 3rd, 2017, 09:32 PM   #22
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Note also that the help file recommends that Gain, Reset and Rate be Floating Point type tags. You might wish to do that before trying to use any automatic PID tuning.
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Old November 4th, 2017, 08:41 PM   #23
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Thank you Bernie, I have a few days off next week but will go through all this when I return to work, I really appreciate all the help I am getting it is a big learning curve for me.
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