SLC Timer Glitch

Is there any chance that the timers acting so strangely are located in subroutines that aren't being called when you observe the odd behavior?

i have had this issue with a micrologix before.
my solution was to use the smallest time base.
i did talk to ab and confirmed later that there was an issue.
hope this helps,
james

James Mcquade said:

i have had this issue with a micrologix before.
my solution was to use the smallest time base.
i did talk to ab and confirmed later that there was an issue.
hope this helps,
james

Click to expand...

wow. yes that does help. I'll refactor to use 1.0s timebase and see what happens.



sidebar: there is a bug in my last attachment. on rung 0010, the [XIC B3:0/5] branch should be removed.

Cleaned up, with 1.0s timebase, TON is 1s; trigger is 819.2ms at 1, then 819.2ms at 0.


@JamesMcQ: did issue occur with timebase of 1.0s, or 0.01s, or both?


Update: added case with 0.01s timebase

SLC's have been around for almost 30 years, I would be really surprised if there was a "glitch" that has only just come to head. I doubt a search of the RA knowledge base would even return any results.

Steve Bailey said:

Is there any chance that the timers acting so strangely are located in subroutines that aren't being called when you observe the odd behavior?

Click to expand...

+1

I was thinking the same thing, maybe a conditional call of the subroutine so sometimes the OP is viewing it while it's not called.

chelton said:

I think you will find the issue is more to do with the HMI momentary contact, and not the timer.
Some HMI's that have a momentary button, are supposed to set a bit "high" for a defined period, then set the bit "low" again. This doesn't always happen. Sometimes the bit does not reset.
I find it better to set the bit with the HMI, then reset the bit in the PLC logic.

Click to expand...

Many HMI and GUI design app have that fault, you can typically force it to occur by pressing and holding the button, then while holding slide your finger or cursor off it. while it releases the button that way it does NOT actually send the button the UP command from a mouse or key. A lot of design apps can be programmed X action on mouse down, Y Action on mouse up. If you slide off before releasing the mouse button you actually never send the mouse up command to the button. Which if the opposing action is present in that part of the buttons commands.. fails to execute.

There is usually a third option "While Down". In my old college days I used that to hide things and mess with instructors when I did my programming classes. The button would be down just long enough to see something flash by if you watched as you clicked it. once they figured out to hold it down to keep it on screen, I played other games with my programs.