Latch an Unlatch circuit

[BeepBob]

Hello All,

Can someone see what I did wrong here.

My "PA" bit never seems to get energized despite hitting "SOFTKEY7" many times

 

[BeepBob]

This is weird...

I simplify the logic...to see if I can even energize one bit...and it seems like

"flag 1" doesnt get energize...

I replaced "softkey 7 toggle" with "flag 1" to see if there is any difference.


a search only shows one OTE on that rung

this is perplexing.


This is a PLC5-40E by the way. I've haven't encounter this behaviour before. There is no other instruction , block read acting on those bits

 

[OkiePC]

What software are you using?

It looks like RSLogix 500 or RSLogix 5, if it is either:

Is something writing to the whole word that contains that target address?

Is the ladder file in question being called by a JSR instruction?

 

[drbitboy]

Is the ladder file in question being called by a JSR instruction?

^ This.

Also:

1) Click the yellow Downloads link above.
2) Click the [Allen-Bradley] link on that page.
3) Search for [ALTERNATING METHODS.pdf] on that Allen-Bradley page.
4) Downlink and read that PDF.

 

[BeepBob]

^ This.

Also:

1) Click the yellow Downloads link above.
2) Click the [Allen-Bradley] link on that page.
3) Search for [ALTERNATING METHODS.pdf] on that Allen-Bradley page.
4) Downlink and read that PDF.

Wow treasure trove. Thank you!

also There is a JSR to the ladder in question.

The field PLC works as expected. I just download the same code the another test PLC5 and disable all BTR and BTW blocks so I can toggle stuff without being over written. I must did something extra..

 

[drbitboy]

There is a JSR to the ladder in question.

Is there a JSR calling the ladder program file with the JSR that calls file #90?

Also, in the first post, why are the XIC N46:39/8 OTL N46:39/11 instructions on separate rung ...21, and not on a third branch on rung ...20?