RSLogix 5 data cross referencing

I'm fairly new at this programming with Rslogix5. I'm having a problem chasing some data in a program @ work. I'll try to give as many details as I possibly can. We are running 5/40s on DH+. I have a bit (N18:22/7) that is being messaged from one node (sub 3)to another node (central). It arrives @ central as N15:22/7 but is copied to N20:201/7 as well as N22:201/7. My problem is that when I tried to find out where it went after it arrived (MSG) to central I came up empty. I tried cross referencing and find N15:22/7 but I came up with nothing. Central MSGs this data to a VAX where it is manipulated for the control room. What I'm trying to find out is how do I find a word, bit ect. when it is messaged to another node and then copied into another location before it is messaged out of the program again. Thanks.

Look in your cross reference for any instructions that work with the word, N15:22, or any instructions that deal with files that would encompass N15:22. If you can, do a screen capture of the cross refence for anything dealing with N15, post it here, and we may be able to show you.

If absolutely nothing in the PLC is manipulating that address, then it may be nothing but a memory location that the VAX comes down and reads.

Where the problem lies is that I have a bit that is being messaged into another node and into a data file (N15:22/7). This bit is not being manipulated in central. Central MSGes #N15:13 length = 12 to the VAX. This is what makes it difficult to find it in central's program. It only is handled in the indexed address of the MSG command and in the indexed address of the copy command. I sort of knew where it was going so I hunted it down manually. What I am trying to do is figure out a method to find out where it is being moved throughout the program when it is only being copied or MSGed out ect.

Pull up data file N15. at the bottom right select the view binary/subelement. Now at the bottom center click usage.
If your messaged data is being used at bit level you will see an X
if it has been placed into a ladder program. If you see a W at the far
left it is being used at the word level. It could be burried some
where like in a copy block with a length of 2-20 or so-on.
Can be hard to find sometimes.

Thanks guys I guess I was looking for an easy solution and sometimes such a beast doesn't exist.

Just another quick ?. When I pull up N15 data file I see a F or a FW between the word address and the bits. Usage and binary/subelement. Can someone please explain what this means. Thanks again.

From the help file:

Display Usage/Display Data
Toggles between Usage and Data. Usage lets you see which addresses are being used in the project file. You can also learn how each address is being used in the project file. For example, you can learn if an integer address is being used as a word address (W) to hold an integer value for your project file, or whether it is being used as a parameter in a file (F) instruction to hold source or reference data. This button toggles with the Data File button. Click Data File to return to the Data File dialog, where you can view the data values for addresses in your project.
In the Usage dialog select the Element Only radix to view whether the address is being used in the project. To view how the element is being used make sure that Binary/Sub element radix is selected. The following table shows what the symbols written to each cell mean.
This Character Means the address is Example(s) might be
. Not being used in the project file Unused word or bit addresses or, when monitoring I/O force tables, a bit address that is not forced.
X Being used in the project file Used word or bit addresses.
W Being used as a word address in the file Greater than or Less than instructions (GRT, LES)
F Being used as a file address in the project File Fill and File Copy instructions (FLL, COP)
WF Being used as a word within a file in the
project Sequencer instructions
(SQL, SQO)
Rockwell Software Inc., 1997, 1998, 1999, 2000

This Character Means the address is might be
. Not being used in the project file Unused word or bit addresses or, when monitoring I/O force tables, a bit address that is not forced.
X Being used in the project file Used word or bit addresses.
W Being used as a word address in the file
F Being used as a file address in the project
WF Being used as a word within a file in the project

From the help file





edit: Note to self -> Must start typing quicker!

Sounds like your (central) plc is being used as a data collector from the other stations, and then passes it on to the VAX. There's a good possibility that it does nothing in the central PLC, except occupy a memory location.

After reading all the informative post I now realize that what I was really wanting to know was how do I follow a bit, word or file that has been MSGed to a node (central) if it is only occupying a memory location so it can be MSGed out of that node (central) again. Especially if it is moved or copied to another address. Is there a method to trace it as the data is transfered throughout the logic.

ptine said:

After reading all the informative post I now realize that what I was really wanting to know was how do I follow a bit, word or file that has been MSGed to a node (central) if it is only occupying a memory location so it can be MSGed out of that node (central) again. Especially if it is moved or copied to another address. Is there a method to trace it as the data is transfered throughout the logic.

Click to expand...

Yours is a common example of a central PLC, aka a data concentrator, for upstream data flow to a Factory Information System. If the data flow is not clearly documented by the original system integrators then its left up to the people maintaining it to figure out how its done. Sorry, there is no obvious tool in RSLogix that will self-document it for you.

Thanks for the info guys. I spent a considerable amount of time trying to find some sort of tool that would help out.