SLC 505 MSG Configuration Hints

Hi all,
New to the site and am glad you all are here. I am having trouble finding a MSG configuration example to get me jump started and am hoping someone can can help me out or link me please.

I am trying to set up a MSG read (or EEM, whichever is easiest) instruction so that one SLC505 can read the status of file N7:0 in another SLC505. They are on the same local IP network. All I need is 1 word, really just one bit. Rockwell's help section sucks.....

Thanks in advance!

Oh, did I mention that Rockwell's help section sucks??

Going off memory here...

Start a new rung and purchase MSG instructions it.
Configuration file takes something like 50 words for ethernet, so create a New data table large enough to hold it. Set configuration file to the start of the new data table.
Click on "message setup" or "message configuration" - something like that.
Pick message type - "Cif read", I think
Select "multihop", which opens another tab. In the new tab, enter -IP address of plc you want to read from
Go back to first tab. Enter address you want to read from target device and where you want to store in in this device. Number of elements (words) = 1

That's about it. Decide how you want to trigger, maybe using a continuous timer.

I remember seeing something like 51 while trying to set up the read instruction. What you are saying seems to echo that. Ok, so I need to add some words to the N7 table, ie N7:0 to at least N7:51?

I would set up a completely new data table for configuration. Say N9:0 to N9:60.

The most straightforward way to transfer data between two SLC-5/05 controllers are the SLC Typed Read and SLC Typed Write message types.

Don't mess with the EEM or CIF functions. You don't even have to use "Multi-Hop", since the SLC-5/05 controllers all support good old "Allen-Bradley Ethernet" protocol.

MSG instructions always use a block of controller memory to store their configuration and status. It's called a Control Block for that message, but it's really just an ordinary section of an ordinary Data File. Some other controllers have a dedicated datatype for message control blocks, but in the SLC-5/05 you just use ordinary Integer data files.

I always set up a separate Data File to use for MSG control blocks. Don't use N7; it's far to commonly used for other stuff.

The control blocks are different size depending on which network port you are using. If you're using the old-school DF1 or DH485 or DH+ networks, each MSG instruction needs a control block of 14 words. If you're using Ethernet, the control block needs to be 51 words.

The data files and lengths in the "This controller" and "target controller" should be fairly straightforward. The minimum amount of data you can transfer is one 16-bit Word. You can't read or write a single bit.

MSG instructions execute when the preceding rung conditions go from false to true. Do not attempt to manipulate any of the status flags except for .TO, which you can set =1 to manually time out the MSG.

If you are using a self-resetting timer as the trigger, I also recommend using an XIO instruction addressed to the /EN bit of the control block (bit 15). This will prevent the message from being put into the messaging queue more than once if it hasn't completed before the timer times out again.

And this is more general Forum advice: You catch more flies with honey than with vinegar.

While I didn't write the RSLogix 500 Help files or the SLC-500 User Manuals, I have written several of the Knowledgebase documents and literally hundreds of posts on the PLCTalk forum about how Rockwell Automation communication networks and instructions work.

I've got a thick skin, but starting your participation in the forum by saying the documentation that I rely on daily "sucks", and then repeating it for emphasis, doesn't increase your chances of getting high-quality advice from expert users.

Thanks for the insights guys.

Ken, you make a good point with the vinegar analogy. Vinegar is usually sour no matter which perspective it is viewed from I suppose. Especially on an initial post like that. Frustration got the better of me, please accept my apologies.

Did you ever get your message instruction to work?

Ken's absolutely right about Communication Command - Select 500CPU Read (or Write). He's also right about the "MultiHop", although it's necessary for ML1100 / ML1400 messaging over channel 1 (Ethernet).

Typically, I use /DN, /TO and /ER bits to trigger MSG. If there's only one, trigger it on a First Pass, then every time the MSG is /DN, /TO or /ER. If more than one, cascade them by triggering the second MSG after the first one is /DN, /TO or /ER. This will allow MSG to trigger as fast as possible.

Haven't had a chance to download the table mods yet. RSLinx v3.60, which we upgraded to last month crashed on us today. Spent some time on hold with RA tech support, finally got linked to a patch (actually 10 of them of the manual install variety). Plan is to complete the patch installs tomorrow morning, then will have to wait until the equipment is idle to download the programs w/new tables. Thanks to you all, I think we are armed and dangerous enough now to do some real damage!

Maybe a Ford and Chevy opinion thing, but Rockwell / Allen Bradley seems to me to offer hardware that is unsurpassed. Their software usually works decent from my experience, but this last month has been quite challenging for us with the upgrades. We have a L35E Compactlogix that was set up at V19. We recently purchased a L33ER that requires a V20 or above. 4.5G download for the version upgrade, wow!! Got V21 installed only to find out that we could could not get comms with the L35E because it doesn't support higher than V20 and the software is not backward compatible, doh! We had a choice of running V20 to talk to both, or run V19 and V21 both which is what we opted for, so far so good. Then Linx crashed today lol. Oh well, Murphy's getting his jollies with us right now it seems.

I am doing something similar to this except I am trying to message from a SLC 505 to a control logix but I can't seem to get the two talking. I have them conneted via ethernet using a stratix 5700. Will this change my "MultiHop" path when configuring the MSG in SLC505?

Welcome to the PLCTalk forum community !

Your question is different enough from this old thread that I think it deserves a fresh post so folks don't have to read through related 2014-era stuff before considering your application.

Go ahead and post followups on that thread:

https://plctalk.net/qanda/showthread.php?p=937906#post937906