Working with DAY of the Week on a CMore...

I have been asked to add Individual Day of the week start and stop times, for each day, to a CMore panel feeding a AB Micrologix 1400...I have found a System tag in the CMore that spits out an ASCI string ie MON, TUE, etc, but i am wondering how/where to do the logic to compare that string to a preset start/ stop time for each day...Brain farts...
Any IDEAs oh great and wonderful PLC Wizards???

The tag is..." sys day week "

Can you use the real time clock in the ML1400 instead of the HMI? The day-of-week is stored as an integer, making comparisons simple.

I didn't know that! OK, now to restart the VM and chase down the list...Thanks for the pointer!!!!


(after one or two of these):nodi:

Yes, it will be easier to use the PLC registers rather than the C-More.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1763-rm001_-en-p.pdf

RTC details start on page 51



-Eric

A word to the wise... you need to be careful with the 1400's real time clock if you intend to allow the user to change the time via the HMI. This is typically done by copying integer registers (modifiable by the user) to the corresponding RTC function file registers. HOWEVER, the PLC will FAULT if you attempt to transfer invalid date values. April 31st = instant fault. This gets even more interesting when you consider that the number of valid days in February depends on whether it's a leap year or not. To create a truly bulletproof system you'll have to account for this in your logic.

See this thread for more information:
http://www.plctalk.net/qanda/showthread.php?t=75121

Thank you guys, we pulled that one out of the deep, dark, recesses of my feeble brain cells after a late night in a strange hotel room....
I was able to set up a DOW section, and then do a bunch of Equal Compare instructions to accommodate the various Start/Stop times they wanted...and all the associated logic changes to prevent the machine from running as it was designed...So what else is new...Just another day in the life of the Field Service 'Person'...