Yes, looking at a print out
Progress....Great!
Yes...
There are other variables but these are common ones you will run into.
%I = Digital Inputs - usually real world inputs or directly related
%Q = Digital Outputs - usually real world oututs or directly rated
%M = Internal memory bits
%R = Internal Memory Registers 16 bit but can be combined to a DINT for 32 bit numbers, or a REAL for real numbers,.....etc.
%AI = Analog Inputs
%AQ= Analog Outputs
Are you looking a printout or text file of the "similar" logic?
Is the "similar" logic on your PC also? You could export the variable name list and import it into the one you are using. If it appears the logic is that close.
Are you using LM90 or Machine Edition?
..
I'm using LM90 as that is the application used on the original.
The "similar" logic was that documented when the machine was first commissioned.
The logic extracted from the PLC was the result after the tool had been in use and might be called "revised". Some aspects of the original configuration and function were discarded, and some added. I would say 80% directly compatible overall, with the "MAIN, START and MANUAL blocks 95% in a one to one comparison.
So I have a "paper copy" of as delivered logic WITHOUT numeric references i.e. %R,%I,%M, %Q, etc. only nick names.
And,
I have the electronic file of the current logic, with it's many changes, extracted from the PLC, without the nick names or descriptions.
Only rung numbers, ladder figures and reference identifiers by type and number.
Combining the two is the puzzle before me presently.
I have spent some time with the GE manuals that are readily down loadable from GE (Thanks for that!) I understand the reference functions I, Q,R,M,S etc. There are no analog modules in this unit, only I/O logic and relays. (4 modules) .
Q and I references are mostly matched to hardware.
To date, I have an EXCEL file of some 165 references, (4-1/2 pages), less than 1/2 populated with nicknames, and less than 1/3 with reliable descriptions.
A start! ;-)
One internal Memory reference M0800, with nickname "READY, is the contact that controls subroutine calls that contain all the "work" done by the logic. This same reference shows up on the final 5 rungs of the "MANUAL" block, as contact that energizes a set of MOVE BIT instructions that sets several internal memories (M0529-M0533) with the constant zero
Also, this same "READY contact controls a MOVE WORD instruction that Takes the value LED1 and outputs to %R0001. %R0001 is set to CONST 0 as a First Scan instruction in the START subroutine block. This reference appears significant!
I can not yet find a location where this M0800 originates. There are no obvious mechanical keys or switches with the GE90/30 PLC, and the "Service Mode" key switch is associated with I0007.
I still see no way to assign an LED on the MMI-200 software to a specific logic reference. I have followed several LED coils back through logic to discover their origin contacts. But it seems incorrect to assign the key pad impulse that directly. Such connection would only serve to "light the lamp". I will soon build a new project and assign R0001 to LED and see how things shake out.
I feel that I am on the cusp with this new language, 'just not there yet.
Perhaps I am "over thinking this thing", perhaps the eureka moment is yet to come.
Thanks for your assistance.
comments always welcome
Cal