AB SLC 5/05 Ethernet MSG Errors

mrdegold

Lifetime Supporting Member
Join Date
Mar 2003
Location
croydon pa.
Posts
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My problem of the moment (Well at least the one I’m hoping you can help with.) is.
I have Allen Bradley SLC 5/05 Processors on an ethernet network I am using some message (MSG) commands across the ethernet mostly for equipment status information. We have 5 or 6 so processors running this instruction. All were running fine I thought when I started to look into including the functionality from one machine to another I found that one of these message commands was in continuous error. I am getting mostly two types of errors
1st) D5 – Connection timed out by network
2nd) D8 - Connection was broken
As best as I can tell the Processor that is initiating a MSG read (SLC 1) is working fine I've traced the action of the MSG instruction using the status bits. It looks like everything from SLC 1 is working correctly. I am thinking that it is the Processor that is being read from (SLC 2) that is the problem. SLC 2 is on the network I know this because I can Ping the address and am currently running a trend using RS trend from SLC 2.
We are doing some maintenance work today that will require SLC 2 to be powered down. I am hoping that when SLC 2 is powered back up the Message instruction error will go away.
I think what I’m shooting for from this community is a plan B. In case the cycle power idea does not work.

As always thanks for the help
Michael
 
I think that you're describing the MSG instruction in Processor 1, which is reading from Processor 2, that is returning an error code in ladder logic. Is that correct ?

Usually MSG error codes mean what they say; that Processor 1 is sending a request to Processor 2 and is not receiving a reply, and is enventually timing out. On Ethernet messages this takes about 30 seconds if I recall correctly.

Are both CPU's on the same subnet ? One common oversight is for a message to pass through a router or gateway, but the target CPU does not have a proper "Default Gateway" address in it's configuration.

How many MSG instructions are you triggering at once in this SLC-5/05 CPU ? Do any of them function correctly ?
 
Ken
Thanks for the reply.
You are correct the MSG instruction is running in SLC 1 reading data from SLC 2. Since the MSG instruction resides in SLC 1 that is where I see the error code.
The Message Time out setting is set too 23 this is the same setting I am using in all the other MSG instruction on this network.
The ethernet addressing has been double-checked and all PLC processors reside on the same subnet with the same default gateway as well. (My plant does have 2 subnets one for PLC's and one for Computers)
I checked all the MSG instructions I have running within my network (which is 5 in addition to the problem instruction) the most MSG instruction in anyone of my processors is 2 and those are running fine. There is only one MSG instruction running in the SLC 1 processor, which is not working correctly. I did check all my other SLC processors and all other MSG instructions are running fine.
Hope this helps.
Thanks again
Michael
 
MSG Block

Are you doing continuous message blocks between different processors or only calling the message blocks when data changes. If you are constanstly enabling the message blocks thru scan time or timers, you could be casuing the problem by overloading the network. If it is a network problem, you could disable the msg blocks on the other processors and see if the problem clears up any.


Please let me know what you find, I have a similar system that will be using 5 505's to message data back and forth.
 
Well I just powered up SLC 2 and the MSG instruction in SLC 1 is now working. The new question is for how long will it before or if it errors again?
I was and still am running this message command using a timer. Before I started to trouble shoot this problem I was running this message command every 5 minutes (It is for a raw ingredient tank level and will not change so fast that I need update any faster)
I would still like to if I can have a plan B in my back pocket that I could use if needed.
For now I’ll keep a close eye on the system and see if I will need to add an alarm in case of error.
Thank you all for your help, as I like to say it's nice to have somebody who speaks my language

Michael
 
Well it’s been about two weeks since we restarted the SLC 2 all has been ok. Then this afternoon we started to see problems in our SCADA system, which is ethernet with SLC 2 we were getting error messages when we would try to reset an alarm that the tag had problems. I went back and check the MSG command that was the problem before and it was in error.
I replace the processor then in less than an hour the same problem started to occur I have just replaced the power supply in hopes that it is the problem. Now I am waiting and watching to see what happens next.
I was hoping to get some opinions from all the experts on this forum about this to hopefully point me in a direction in case of failure.
Thanks
 
mrdegold,

Are all the processors 5/05's? If so, are the programs with the MSG instructions native 5/05 programs? i.e. were they originally written for the 5/05 or were they written for a lower processor and then upgraded to the 5/05?

If not all the processors are 5/05's and you are using, for example, a 5/03 with a NET-ENI module, you will need to configure the MSG instruction in the 5/05 as a multi-hop. You might want to try this anyway to see if it clears up your problem.

If the program was originally written for an earlier version processor, try deleting the rung with the MSG instruction in an offline copy of the program, verify the project, and then reprogram the rung, reverify, download and run.

I may be shooting in the dark, but I recall having some issues with a MSG instruction in a 5/05. If I remember right, the multi-hop setup fixed it.

Good Luck,
Jeff
 
jshiepe:

Thanks so much for your hint on the mulit-hop. I am using a 5/05 to try to msg to a 5/04 with a NET-ENI module, and got the "Connection was broken" error immediately upon execution. Using the multi-hop fixed it right away. There is no indication in the help file as to what multi-hop did, so I didn't try it until I read your message.

Thanks again!
 

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