Rslogix 5000 Beginner

Vager

Member
Join Date
May 2018
Location
NY
Posts
8
Hello all,

Just beginning to work with the Rslogix5000 platform so hopefully i can phrase this question clearly and with the right terminology. What would be the most efficient way to search for tags that are communicated between several control logix PLC's connected via ethernet? I seem to find myself looking at a lot of MOV instructions that are reading/writing arrays from one PLC to another. Feel like i'm stumbling around quite a bit and there must be some easy way to find the source and destination relating to this data. Any help or insight into this issue would be appreciated.
 
It sounds like data from various bits of the program that need to communicate with another PLC are being stored together and transferred as a single tag. It makes more sense if you look at the values being copied in binary. Then each bit represents something, and it is usually organized neatly so that you can find what you are looking for.

Once you have the "bit of interest" you can search for that bit in each program and see what it is doing, and use cross-reference to find all instances of a particular bit and track it throughout the logic. Ctrl+ F will get you started, or just right click on the bit in the ladder.

Also, a MOV instruction doesn't write to other PLC's. The MOV instruction, however may be doing what I spoke about above, and putting the data where it needs to go to be transferred.
 
Last edited:
Thanks for the info! I have been having success in referencing the binary values and most of what i'm looking at is organized in the controllers routines titled as Read_Data and Write_Data. The MOV instruction has me a bit confused only because that is often the only instruction i can seem to find during cross reference in either program. I gather from what your saying is that if i dig deep enough i should be able to find some sort of MSG instruction or something similar that is capable of moving the data?
 
To expand on Bernie's reply , select controller tags (2nd item in the left side explorer) then click show and pick produced to see exported tags (if any) or consumed to see tags sent by other PLCs .
 
Hello all,

Just beginning to work with the Rslogix5000 platform so hopefully i can phrase this question clearly and with the right terminology. What would be the most efficient way to search for tags that are communicated between several control logix PLC's connected via ethernet? I seem to find myself looking at a lot of MOV instructions that are reading/writing arrays from one PLC to another. Feel like i'm stumbling around quite a bit and there must be some easy way to find the source and destination relating to this data. Any help or insight into this issue would be appreciated.

Nobody else mentioned this, but, every 5000 Series ethernet interface has a Web Page, and, on that Web Page, you will find a detailed list of Originator and Responder I.P. addresses. THIS is really the starting point for your search. It will allow you to manually generate a list of IP addresses that are initiating and responding to communications.
 
And nobody has mentioned this either...


If another processor is writing to this one, you will not be able to get a cross-reference, or a search, or anything, to tell you where the data is coming from....


Which is why I always prefer Read messages, at least a cross-ref will have a "Destructive" MSG listed.


The "Destructive" column in the cross-reference is very useful, it tells you which of the instructions found can change the value of the tag. You can sort the X-Ref listing by this column to get all the destruction instructions at the top... very handy ...
 

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