studio 5000 ultilzation chalenge

[Mark Bromley 1]

Hello ,

I have an interesting programming chalenge and i was wondering if anyone has ever had a similar request?

I have been asked to monitor and record how often a machine is running and express this as an overall machine ultilization, The logic for the machine run verses machine down is pretty strait forward the problem is that some portion of the machine downtime is with the power off and no power to the proccesser.  ThIs would all be done in Studio 5000.

Thanks

MB

[Joe E. 259]

What kind of time period are you talking about? Daily, per shift, weekly, for the lifetime of the machine?

The PLC can easily accumulate machine run or stop time (using RTO instructions or a periodic task for more accuracy) while the PLC is running.

If you trust the RTC (Real-Time-Clock) to be accurate, you can use a GSV instruction to grab the date/time every scan. I usually use the GSV to grab the Wall Clock, local time, but in this case I might use UTC in case it's down through a time change (not sure if the RTC automatically updates for DST or if it will do so while the PLC is off). Then, on first scan (using S:FS or the power-up handler), you can grab the time again and find the difference between them to see how long the processor was not in Run mode. This should be accurate to within 1 or 2 scan times.

If you're just interested in the times for the current shift, you can have your RTO/Periodic task accumulate run time and just subtract the shift beginning time from the current time to determine total shift time. Then you'd have your run time percentage. The time subtraction will be a little trickier if your shifts span days (like our 3rd shift starts at 10:30PM) but should be manageable.

 

[pcmccartney1 141]

What you are being asked to provide is called OEE (Overall Equipment Effectiveness) with books and websites dedicated to the subject.

[PLCMentor.com 60]

Ideally you would have some sort of SCADA system that would log downtime events and be setup with scheduled runtime for your machine.  As has been mentioned, you are basically being asked to achieve a poor mans OEE.  As you mention, keeping track of machine run versus stop time is pretty easy.  Joe mentions using the system clock to avoid issues with powering down the controller.  You may also want to add an additional variable to be stored.  Possibly a daily expected runtime number that would allow you to calculate some basic OEE number that has some meaning.  Just logging up and downtimes doesn't let you know if the machine is operating outside its expected run periods (ie, planned downtime versus unplanned downtime).