Help finding bit in RS Logix5000

NetNathan · Jun 21, 2021

I cannot find what controls this bit in logic.
Some kind of master bit.
search only shows this bit
Control Logix 5571 CPU

Any ideas??

parky · Jun 21, 2021

Could be it's on some coms, or as it appears to be part of an array perhaps the other reference to it is by word.

NetNathan · Jun 21, 2021

parky said:
Could be it's on some coms, or as it appears to be part of an array perhaps the other reference to it is by word.

Shouldn't FIND show word location also?

parky · Jun 21, 2021

I do not do Rockwell any more(that's another story) , but it was just a suggestion, I know that some IDE's have problems even text based search rather than symbol/tag can give unreliable results. The other possibility is it does not exist elsewhere but retained as true.

NetNathan · Jun 21, 2021

parky said:
I do not do Rockwell any more(that's another story) , but it was just a suggestion, I know that some IDE's have problems even text based search rather than symbol/tag can give unreliable results. The other possibility is it does not exist elsewhere but retained as true.

Yes... I steer away from Rockwell also, bit got stuck with this nightmare logic program. Very bad logic naming...

Found the problem though, this equipment has 6 E-Stops on Flex IO and hardwired also and one had faulty contacts. Problem went away after fixing contact. Stroke of luck found it.

nehpets · Jun 21, 2021

If you look in your controller organiser (on the left) and scroll down to I/O configuration, you should see something labelled as B1_MSTR this is some form of input/output device. If you right click on it and select cross reference, then select by tag, it should show what it is as long as it is documented.

drbitboy · Jun 21, 2021

NetNathan said:
I cannot find what controls this bit in logic.
Some kind of master bit.
search only shows this bit
Control Logix 5571 CPU

Any ideas??

Doesn't the :I in B1_MSTR:I.DATA[2].1 indicate this is from an input card of some type?

NetNathan · Jun 21, 2021

drbitboy said:
Doesn't the :I in B1_MSTR:I.DATA[2].1 indicate this is from an input card of some type?

I thought I would have found some sort of reference to rack and slot as I did with some of the other IO I was troubleshooting.

nehpets · Jun 21, 2021

Not if its a 3rd party device (ASi bus, Anybus etc.)

OkiePC · Jun 21, 2021

Right click, Go to Cross Reference. From there, you will see a list of references to that address. There is a column labeled "destructive" that indicates items in the list (Y or N) that can write to that address. Click (or double click, can't remember) on an item in the results list to navigate to the code it references.

On the upper left iirc, there is a drop down that is populated with that address or a browse tree that lets you navigate to the root of the element containing the bit if it is a member of a group that could be "destroyed" at a higher level. The "Find" tool is Logix5k is not nearly as useful as it is in RSLogix5/500, but the cross reference is quite useful.

dmroeder · Jun 21, 2021

That bit is aliased to an input, there will be no coil, it's the input that controls it. Look for whatever device in the tree is named B1_MSTR, slot 2 input 1. Point I/O maybe?

daba · Jun 24, 2021

dmroeder said:
That bit is aliased to an input, there will be no coil, it's the input that controls it. Look for whatever device in the tree is named B1_MSTR, slot 2 input 1. Point I/O maybe?

Spot on ! Always look at the alias information in blue underneath the tag address.

Hint 1 : Any tag (in this case the blue tag) with a colon ":" in it is an I/O tag, you cannot create a tag with colons in.

Hint 2 : Learn to use the cross-reference facilities, they WILL save you hunting aimlessly, and don't forget when using the cross-ref window you have 3 different "views" of the information presented .... check out the tabs at the bottom of the screen.

I don't believe there is anything you can't trace back to source using cross-referencing - superb tool, and needs to be understood.

Hint 3 : the "destructive" column in the cross-reference window is without doubt the most useful way to sort the results. Non-destructive, ignore it, Destructive tells you what changes it, a very powerful debugging tool indeed !!!

daba · Jun 24, 2021

I am going to post this in CAPS, feel so strongly about it..

THIS PROGRAM YOU HAVE SHOWN A SNIPPET OF IS SO OBVIOUSLY A CONVERSION, THE TAG NAMES ARE COMPLETELY MEANINGLESS.

If you are now "in charge" of this program, make it your task to put some meaningful tag-names in place of the converted addresses.

Take your time, work out what each "address" does, what it means, and change its name to something that means something, that you, your colleagues, and all yours and their successors will thank you for.

Even if it takes you a month, a year, or whatever, it is worth doing.

Phrog30 · Jun 24, 2021

daba said:
THIS PROGRAM YOU HAVE SHOWN A SNIPPET OF IS SO OBVIOUSLY A CONVERSION

Conversion from what? SLC? PLC? Where they used tags?

NetNathan · Jun 25, 2021

daba said:
I am going to post this in CAPS, feel so strongly about it..

THIS PROGRAM YOU HAVE SHOWN A SNIPPET OF IS SO OBVIOUSLY A CONVERSION, THE TAG NAMES ARE COMPLETELY MEANINGLESS.

If you are now "in charge" of this program, make it your task to put some meaningful tag-names in place of the converted addresses.

Take your time, work out what each "address" does, what it means, and change its name to something that means something, that you, your colleagues, and all yours and their successors will thank you for.

Even if it takes you a month, a year, or whatever, it is worth doing.

Yes I found the tag I was looking for.. that was actually easier than figuring out what is going on in the rest of the logic.
You are right, the logic is a total abomination..
It was converted from GE RX3i and they used the IO from the GE programs for about 75% of the tag names!!!!!
It is a friggin nightmare to figure out, without original GE Logic to use as x-ref.

The logic is rather large and involves 2 moving bases that are moving in and out of a bottom load furnace, also going through a cooling chamber with doors
The location and movement of the carts is near impossible to follow. Even the integer tagnames are referenced to the GE IO registers.
Who the frik would do this is beyond me...it makes no logical sense at all.

This a perfect example in what NEVER to do when writing logic.....

Help finding bit in RS Logix5000

NetNathan

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