One Shot Rising with input

[Krilun]

I'm using RSLogix 5000 Function Block Diagrams. I am trying to increment a counter using One Shot Rising with Input (OSRI) block. The OutputBit never changes from 0. Even when I directly set the input the OSRI to 1, the output is still 0. I have tried to enable the EnableOut bit and set it 1 and still nothing happens.

Any suggestions?

-Ken

 

[Ron Beaufort]

not sure I understand what you're asking - but here's my best guess ... it IS coming on, but it's only on for one scan - therefore you can't see it happening on the screen ...

tip: for testing purposes try putting something like an ADD or CTU downstream to "trap" the pulse ...

another guess ... maybe the FBD routine isn't even being scanned ... is it a new one? ... is anything/everything else on that diagram already working? ... maybe you need a JSR from your Main-Routine to tell the processor to scan your FBD ...

if this doesn't help, consider posting your .ACD file ... I'm sure that someone here can help nail down your problem ...

 

[Krilun]

the main routine does the call the routine and returns successfully.

the easiest way I can describe my problem is I have a 1 going into a one shot, and 0 coming out. I am trying to use a CTU to trap the signal to accumulate my counter. I created a tag "test" (bool) and set its inputbit to 1. I run that into one shot and nothing ever comes out.


?? Frustrating

 

[Ron Beaufort]

another guess ... you can't just put a continuous ONE in ... you have to CHANGE IT (TRANSITION) from ZERO to ONE to make the One Shot give a pulse ...

if this doesn't help, consider posting your .ACD file ... I'm sure that someone here can help nail down your problem ...

 

[BillRobinson]

Another good trap would to be use the RESD function and set a 0 on the reset input block try this:

IF the output pin of the RESD block is =1 you've gotten a 1 from the ONSI block. NOTE use RESD block not the SETD block. The SETD sets the output pin to 1 on the first scan, the RESD starts out as a 0.

I suspect their might be a problem with your upcounter settings.

 

[Peter Nachtwey]

I bet I know

Are multiple one shots using the same bit to save state?
You shouldn't use the same memory bit more than once.

I once had a customer that used the same one shot location many times and blamed the motion controller for not moving. I will never forget.