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  1. #1
    Join Date
    Feb 2013
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    Minneapolis
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    Question regarding timer functions in PCT

    Hey, all. I'm working on a program and I have had issues in the past with timers locking up on me for no reason in PCT and I couldn't reset it. This was a minimum on timer and I'm now reading in the help files that the restart doesn't work when it's set up to minimum on. However, what I'm using at the moment is a cancelable pulse. I am putting in this program into multiple air handlers and just want to make sure I have my bases covered.

    One question I have is the "reset action" isn't very well described here, but my instincts tell me that "wait" does what it says, waits for a command to restart. And "retrigger" auto restarts? Funny that it explains you can change the action itself while the timer is active, but doesn't explain what "retrigger" does necessarily.

    I will attach the "Timer" help file in PDF form for your reference, I'm just throwing this out there to see if anyone has learned the ins and outs of timer functions in PCT, because you can do a lot more there and I trust it more at the field controller level than on Workbench. Tangentially, I learned recently that when you use a Numeric Delay in workbench, they start at 0 when a database restarts. So be careful using those if you are sending a Discharge setpoint to a controller and you're using one of those to tamp down on the number of writes like I was. Set up some redundancies in case it goes out of range.

    Sorry if this was too long. Curious to hear your thoughts.
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  2. #2
    Join Date
    Mar 2018
    Location
    Toronto, Canada
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    3
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    I have had timers freeze up in PCT 10.1 all the time when they are in a hybrid-activty(the modules with multiple states, i think thats what they are called). I started putting timers only in normal activities/modules to prevent this so I don't know if it still happens in PCT 10.2. I've even had some timers appear to be locked up, but it was actually just the PCT commissioning screen that wouldn't update the output "present value" of a timer but the physical outputs of the controller were working correctly.

    From my experience, when "reset action" is set to wait, if you reset it while the input is true it will wait for it to go false then true again to restart the timer. If it is "retrigger", it will start the timer right away without the input from having to cycle false then true. Hope that makes sense.

  3. #3
    Join Date
    Feb 2013
    Location
    Minneapolis
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    33
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    Thread Starter
    I'm reviewing the program I remember having problems with and I noticed two things.

    1. I had the timer action set to "wait". However, I had it defined as a minimum on, which if you'll note from the help file I attached, the reset action has no function when defined as min on or min off./

    2. The logic for the timer was built into an output control only when it's under the "control" state. I almost wonder if the problem occurred when the state table changed from "control" to "off" when it was in the middle of a timed period. hmmmm

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