Omron Ladder logic "Filter Change" Countdown Timer

Wiresplus

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Join Date
Sep 2021
Location
Auckland
Posts
17
Hello all,
I am working on an old machine that has a hydraulic filter that must be replaced every so often.
When the filter needs changing, a signal input comes back to my PLC.


Once the signal is present, only the resetting of the physical device in the filter housing will reset the signal. so far so good.


Now, I want to have a 50hr countdown on that. After 50 hrs, the machine will stop working if no-one has done the filter.



After the signal is reset, and the warning message acknowledged on the HMI, the timer is reset and does not start again until the next time the signal comes.


However, the machine gets turned off every night and the power cycling kills and resets my 50hr timer.


How do I get a non-volatile countdown timer? Or is there a better way to do it?


Omron CP1L-E
 
Last edited:
What model of omron plc?

You can use 60min timer and save hours to word in the DM(or HR) memory area which is retentive.
 
Last edited:
If you use a time driven counter, the value will not reset on the counter.


gtsuport
One thing I probably didn't make clear was that this machine runs for a few minutes at a time. I need to add all these minutes up (the standard timers in Omron seem to be only a delay-on type with no 'enable' input, just a run input that resets the timer on going low).
 
Why not use DM or HR memories, increment the seconds (or minutes) when it reaches 60 add 1 to the Minutes Reset seconds (do the same with minutes & hours) do this while running so you have a run time count in hours & minutes (and if required seconds). Just reset them to 0 after filter clean/change simple.
The alarm would be comparing the hours count to >=50.
 
i have done something like this to track downtime of a machine.


i just used a 1S pulse P_1S that triggered a counter which resets itself upon reaching 59 (or should this be 60?) giving a seconds counter


and then another counter that is triggered by the pulse of that counter which does the same thing giving a minutes counter


and then finally the same as the minutes counter we have an hour counter which would in your case be resettable only by your filter signal
 

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