Is there any hidden instructions outside the ladder logic?

[arpus4KM]

If I'm understanding it correctly.

your DII is using 10h, which is Bit (0001 0000) in Slot 3. or I:3/4 to operate the inturrupt.

you can look at the help file in rslogix 500 and get info on what each of the items in the DII section of the processor file are doing. But I also found this, which explained a little differently.

https://bryceautomation.com/index.php/2021/01/20/slc-500-discrete-input-interrupt/

 

[Operaghost]

So the DII is indeed where it is monitoring that input. The Bit Mask (S:48) is identifying the inputs for slot #3 (S:47). "10h" is actually 0000000000010000 in binary. So that would be input #4 for slot #3, or I:3/4.

The Compare Value (S:49) is identifying that bit #4 must be a "1".

So whenever input I:3/4 has a closed contact, the SLC will jump to Program File 7 (S:46) and execute the code in that subroutine.

OG

EDIT: Ian was faster and Steve was slower but Jesper beat us all

 

[Steve Bailey]

It looks to me like Jesper called it.

The interrupt triggered by the the fifth (10h) input on the card in slot 3 executes a call to LAD 7.

Edit: Ian is faster than OG is faster than Steve.

 

[arpus4KM]

So the DII is indeed where it is monitoring that input. The Bit Mask (S:48) is identifying the inputs for slot #3 (S:47). "10h" is actually 0000000000010000 in binary. So that would be input #4 for slot #3, or I:3/4.

The Compare Value (S:49) is identifying that bit #4 must be a "1".

So whenever input I:3/4 has a closed contact, the SLC will jump to Program File 7 (S:46) and execute the code in that subroutine.

OG

EDIT: Ian was faster

and jesper beat me while i was typing.

 

[geniusintraining]

(I might be wrong, it has been 15+ years since I worked with SLC500)

It looks to me like Jesper called it.

15 years later.... still got it!

 

[shaydzmi]

Fabulous! In less than half a day I was able to solve the problem that has been bothering me for days and days.
Thank you all!

 

[parky]

Damm, I did not see it I was looking at the screenshot Jesper posted so obviously it did not show slot 3 so I should have looked at the post after that.
Must be my age lol,

 

[I_Automation]

Now that your problem is solved looking at the program I have a suggestion that saves memory and a few clicks of scan time.


Every one of the subroutine ladders {except 7 of course) starts with a redundant SBR and ends with a redundant RET, as each one is already a subroutine and will return at the END rung.


That's extra instructions the CPU has to process every scan and if memory is tight deleting those would open a few words, and processing them takes a click of the CPU every time. I wouldn't delete the RET in ladder 7 as the interrupt MIGHT need it.



I know you didn't write this program but I'm just suggesting you don't copy this style.


EDIT: I just went through it and opened 62 words of memory and possibly many uses of the CPU every scan depending on how often the subroutines are called.

 

[shaydzmi]

Dear Administrators and other members,
I have more questions related to this project, should I put them in this post? Or should I create a new thread?
Thank you all.

 

[JesperMP]

New thread.

 

[parky]

Jesper beat me to it, I agree, other members tend to look at the title & if this is not an interest too them or the original thread is getting long winded they may ignore it.