Free Running Clock

dmroeder

Lifetime Supporting Member
dmroeder
Join Date
Apr 2006
Location
Vancouver, WA
Posts
3,601
I have been using one of the status bits off of the free running clock (S:4) on a SLC to control an output. It works really nice for indicators since you don't have to use timers to do it. My question is, does anybody know a similar way to do it in a CompactLogix (or any logix 5000 platform)? Doing it with timers is easy enough, but we try to keep our code the same (or similar) between platforms. Hope this makes sense.

Dustin
 
You can create a tag of type Timer and name it Free_Running_Clock. Create a timer that will reset when it reaches 2^31 counts. Then you can use the bits from the timer ACC just as you use the free running clock bits.

However, the CLX platform supports timed periodic tasks. You can use these to create flasher bits without using timers.
 
Another option is to use the GSV instruction to get the date and time from the processor. Then use the bits from the time just like the S:4 bits. I don't remember at the moment which ones. This works in ControLogix; I've never used a CompactLogix.
 
Dear necroposter, I did indeed use a GSV. The Class is WALLCLOCKTIME and the attribute name is LocalDateTime. You put it in an array of 7 DINTS. My favorite bit is bit 19 in element 6 of the array.

Just kidding about the necroposter thing...
 
GSVTime.png

You are right, I can't remember that far back. However the original post was April 2006 and that happens to be my join date as well. I just connected the dots :)
 

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