Flip flop not working?

g.mccormick · Apr 9, 2019

I found and fixed issue. B3:3 was used in MOV.

g.mccormick · Apr 9, 2019

I will leave that post up as a lesson to myself.

I found the issue and fixed it, there was nothing wrong with the flip flop, there was a mov instruction about 20 rungs below that was setting B3:3/4.

Isn't there a proverb about not seeing forest through the trees?

Dhitzfelder · Apr 9, 2019

Is B3:3/4 used anywhere else in the program?

Especially, does it have any other (U) coils?

EDIT: lol, yep, that'l do it...

g.mccormick · Apr 9, 2019

Dhitzfelder said:
Is B3:3/4 used anywhere else in the program?

Especially, does it have any other (U) coils?

EDIT: lol, yep, that'l do it...

B3:3 was used in MOV instruction. I had searched for B3:3/4 with no hits (beyond mine), but I did not search for B3:3. Lesson learned.

Firejo · Apr 9, 2019

I like the code you wrote.
In the interest of learning, if you ever wanted to do a flip flop at a word level, this works pretty good. The nice thing about this one is that you can "flip/flop" multiple bits independently I.E. if you toggle bit "B9:0.0", bit "B9:1.0" will react. If you toggle bit "B9:0.4", bit "B9:1.4" will react and so on.

g.mccormick · Apr 9, 2019

Firejo said:
I like the code you wrote.
In the interest of learning, if you ever wanted to do a flip flop at a word level, this works pretty good. The nice thing about this one is that you can "flip/flop" multiple bits independently I.E. if you toggle bit "B9:0.0", bit "B9:1.0" will react. If you toggle bit "B9:0.4", bit "B9:1.4" will react and so on.

That's fancy and interesting. Thanks!

Firejo · Apr 9, 2019

g.mccormick said:
That's fancy and interesting. Thanks!

Gotta give credit to Ken Roach. I got it from him, but you are welcome.

geniusintraining · Apr 9, 2019

I like this one for RSLogix 500...

The least significant bit C5:0.ACC/0 changes state every time the timer increments.

0 0 0 0 Timer.Acc=0
0 0 0 1 Timer.Acc=1
0 0 1 0 Timer.Acc=2
0 0 1 1 Timer.Acc=3
0 1 0 0 Timer.Acc=4
0 1 0 1 Timer.Acc=5

http://www.plctalk.net/qanda/showpost.php?p=135485&postcount=12

Bob O · Apr 9, 2019

+1 Mark.
I've used that method so many times and haven't looked back.

BITS N BYTES · Apr 9, 2019

Another winning solution from Ken Roach!!!

30+ years working with multiple PLC platforms!
AND STILL LEARNING.................

g.mccormick · Apr 9, 2019

Mark on yours wouldn't the counter value be retentive? So you would need to be sure that whatever is happening with T4:0/DN is ok to start by itself after a reboot if it was on when plc went down.

geniusintraining · Apr 9, 2019

See here http://www.plctalk.net/qanda/showthread.php?p=135485

Thats where I got it from and started using it a long time ago

EDIT: Man that was a long time ago.... Hey Bob I have another bottle for your Whisky thread

Flip flop not working?

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