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Old November 14th, 2017, 03:17 PM   #1
TheWaterboy
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On/Off percentage

Disclaimer: This might be simple - about to have my first grandkid any day now so I'm up late with my daughter and VERY sleepy during the day so my brain is lagging way behind its usual substandard.

Working with a PLC-5. Trying to calc Duty percentage of a pump. Looking for short cycling, not looking for a runtime.

The math is easy: duty% = [Running time] / [cycle time]
Haven't had to do this particular thing before and it caught me that this isn't dead simple, but again, substandard brain.

I haven't tried an OSR yet, I will while I wait for an easier answer, but how else can you time a single bit from true transition to true transition to get the entire cycle time?
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Old November 14th, 2017, 03:52 PM   #2
sparkie
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For the run time use a tl timer while it is running and copy the accumulated value when the timer is deenergized. Perhaps a retentive timer.

For the total time it depends. Is the process cyclical or is it 24/7 Like a water treatment plant.?
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Old November 14th, 2017, 04:05 PM   #3
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That would catch the running time, But I need to get the cycle time (On time + Off time)

Its 24x7 as needed, no regularity to it. I also have to have 2 time scales depending on which process it being done. One takes minutes, the other takes
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Old November 14th, 2017, 04:15 PM   #4
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So you want time between true transitions. You are dead on using a OSR.
Rung 1 - OSR Logic
Rung 2 - OSR bit true = MOVE Run Timer.ACC to Storage to capture data
Rung 3 - OSR bit false = Run Timer

This will capture time between OSR Pulse. When OSR transitions to true it will capture data. The next rung will reset timer. The next Scan Cycle Timer starts accumulating next cycle time.


P.S. Congratulations!! May it be healthy and happy.
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Old November 14th, 2017, 04:35 PM   #5
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Thanks.
Lets assume this isn't an Enhanced PLC (the ones that can't use the OSR) . How else would you proceed?
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Old November 14th, 2017, 05:45 PM   #6
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Rung 1- XIC Pulse trigger - ONS - OTL (Latch Bit)
Rung 2- XIC Latch Bit - MOVE Cycle Time.ACC to Storage to capture data
Rung 3- XIO Latch Bit run TON Cycle Timer
Rung 4- XIC Latch Bit - OTU Latch Bit

This will keep latch bit true for 2 rungs to Move Data and reset Timer.
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Old November 14th, 2017, 05:51 PM   #7
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That should do it. I got the idea. I kept thinking bits didn't resolve until the end of the ladder (like I/O) I know better so thats my problem today.
Man I need a nap !

Thanks for the help.
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Old November 14th, 2017, 06:24 PM   #8
sparkie
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Quote:
Originally Posted by TheWaterboy View Post
That should do it. I got the idea. I kept thinking bits didn't resolve until the end of the ladder (like I/O) I know better so thats my problem today.
Man I need a nap !

Thanks for the help.
Don't be afraid to. Yea, there are times you have to push through, but I've done it. 19 hours into a job I told them I'm going to take a nap. Wake me in an hour. No point to continue if my brain is useless.
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