I/O Indirect Addressing - PLC 5/80E

relms

Member
Join Date
Feb 2005
Location
Decatur, IL
Posts
4
Got a question if anyone has an answer, that would be greatly appreciated. I am trying to figure out how to compress a robust program. 97% of my processor is used and I am trying to compact it using indirect addressing with I/O. I was trying:

XIC I:[N7:0]/[N7:1] (for example)

But RSLogix doesn't like that kind of indirect addressing. I am thinking about using BINARY files to read and write to the I/O, but that just takes up more space. Any way to indirect address I/O?

Thanks,

Rob
 
sorry ...

Greetings relms,

if you're using RSLogix5, you can't "direct address" down to the bit level except for "B" type files ...

but just as a suggestion ... have you looked for things like "data holes" and unused files? ... if you want to zip and post your .RSP file, we'll be glad to help you try to compress your program ...

and welcome to the forum ...
 
No Problemo

Thanks for the answer, Ron. I was hoping that wasn't the case, but I'll just use up some Binaries.

As far as the rsp, the company probably wouldn't be too happy with me doing that. haha

Thanks for your help. I appreciate it!

Rob
 
If you have gaps in your timer, counter or floating point files, that is you used timers 0-500, and then the next used one is 550, you can move the used timers (takes a lot of time) to fill up the gap, and then drop the unused timers at the end. I mention timers, counters and floating points because they have multiple words per entry.

Just a thought,
Ken
 
Thanks for the reply, Ken. Unfortunately, my predecessors were good at using up all timers and counters. As well as unused words.

The programming is just way too simple, that it takes up 38,000 words to configure around 400 valves. 20,000 for around 180 agitators and pumps.

Thanks for the suggestion though...much appreciated.

Rob
 
relms said:
Thanks for the reply, Ken. Unfortunately, my predecessors were good at using up all timers and counters. As well as unused words.
Rob
How about files? As Ron B. alluded to above, unused files are another source of "bloat". Whether actually created or not, they can take up overhead space. For example, if you have a file (program or data) number 15 and the next one configured is 30, then, even though files 16 to 29 do not exist, each one has 6 words of overhead reserved for it (14 x 6 = 84 words wasted).

I've seen a lot of programs with a lot of 1 or 2 word data files. Combining them into larger files wil save overhead.

Try to keep all internal storage bits in the low words of file B3. There is a break point part way through B3 where bit instructions (XIC, OTE, etc.) change from 2 words to 3 words to handle the higher physical memory address. Bit instructions with file addresses T4 and above use 3 words (maybe 4).
 
There is a break point part way through B3 where bit instructions (XIC, OTE, etc.) change from 2 words to 3 words to handle the higher physical memory address.

If I remember correctly it is 256, once you go over that number you get more overhead. It's in the reference manual, but I don't have it handy.

Ken
 
Ken Moore said:

If I remember correctly it is 256, once you go over that number you get more overhead. It's in the reference manual, but I don't have it handy.
Ken
I can't really remember where I read about it (many moons ago), but I seem to recall that the break point varied depending on the size of the I/O image table.
 
Thanks for the suggestion, Gerry. It's not a problem now, but I'll be aware of it in the future.

When you say "256"...is that the word count of the file or bit count?
 

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