RSLogix500 Indirect addressing question

Good day all, I would like to know if it is possible to use a counter' accumulator value as an indirect address. So it would look something like this: N7:[C5:0.acc]. I tried it and the software wont accept it but I could have sworn I seen it used like that. It might have been RSLogix5 but I don't believe that indirect addressing is different from RSL500 to RSL5, correct? Thank you.

I found my problem. I should have waited five more minutes before submitting this thread. Sorry.

What was the problem?

let's hope that ceilingwalker responds with what he did wrong.

MOV N7:0 N7:[C5:0.ACC] is perfectly valid syntax for the SLC500 series and all the MicroLogix processors. The only thing to be wary of is that the lesser MicroLogix boxes can't have additional data-tables.

I am ashamed to admit it. I was using the wrong type of instruction and the software didn't like it. One of those "couldn't see the forest for the tree's" sort of a thing.

BTW daba, love your avatar! To this day still have both albums memorized.

I'm thinking that everyone wanted you to post your solution so that others could be helped in the future.

dmroeder said:

I'm thinking that everyone wanted you to post your solution so that others could be helped in the future.

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Some how I doubt anyone would try to do something as dumb as I did. I was trying to use an instruction at the bit level but this obviously requires an instruction at the word level. Looking back on it I have no idea what I was thinking. I used a XIC instruction trying to use an indirect address and it made no sense at all. This is why I didn't post my solution, because it was a dumb question to begin with.

ceilingwalker said:

Some how I doubt anyone would try to do something as dumb as I did. I was trying to use an instruction at the bit level but this obviously requires an instruction at the word level. Looking back on it I have no idea what I was thinking. I used a XIC instruction trying to use an indirect address and it made no sense at all. This is why I didn't post my solution, because it was a dumb question to begin with.

Click to expand...

We all have moments, minutes, hours, even days like that. I was once picking up the pieces of someone else's coding, and couldn't work out why a section of code wasn't responding as it should have.

I checked the usual suspects, is the subroutine file being scanned - check, searched for MCR instructions - check, searched for JMP instructions - check, searched for an early RET instruction - check. I'll be honest and state that it was a good 2 hours before I found the TND instruction 35 rungs above where I was debugging !

I should have known better with my experience, but on that occasion, the TND wasn't on my list of things to look for. In actual fact, it turned out to be a life-saver that it was there, because the code I had inherited to debug would have made a mess of the process it was controlling - and that would have been costly.

We learn a lot more from our "mistakes" than any training or tutoring can give you. The school of life is a great learning establishment