Problems with SLC 5/05 MSG instruction over Ethernet communication

alex08 · Sep 30, 2008

Hi, I have a problem with a cpu slc 5/05 (1747-L552), 32k Mem 0S501 series C, I am using the MSG instruction to ethernet communication, it works for a few days very well, but later the communication turns to slow, and sometimes stop for complete. The way that the communication is restablished its making a cycle power to the processor. Below appear a part of the logic that I am using to send and receive information to DVT system by ethernet. Somebody knows if there is another way to configure this instruction and never gets faulted?

widelto · Sep 30, 2008

Show us the logic.....

Sergei Troizky · Sep 30, 2008

Is there a possibility of IP addresses conflict on the network?

alex08 · Sep 30, 2008

I dont think so, agree to the posts that I been reading the problem is about the buffer that this instruction use, it gets full or something wrong happens, attached I send part of the logic.

TimWilborne · Sep 30, 2008

How exactly are you managing the execution of your messages?

alex08 · Sep 30, 2008

Here is the configuration that I am using in the MSG instruction (read/write), I am using 2 instructions to read and 1 to write, the logic is the same in the 3 instructions (shown in my last post).

TimWilborne · Sep 30, 2008

Ok, these screen captures are getting old real quick...I think you can actually post images so we won't have to unzip everyone.

You posted the message configuration, I asked about how you were managing the execution of your messages.

alex08 · Sep 30, 2008

The execution is direct to the plc scan,I mean I am sending and receiving data all the time, you can see these in the logic shown in this post.

Oakley · Sep 30, 2008

most likely your buffers are slowly filling up until they can't do any more messaging.

Try conditionalizing your messaging. How often do you really need the data?

TimWilborne · Sep 30, 2008

So your bits such as N24:0/15 are not managing the execution of the MSGs at all?

You should at least inhibit the rung as long as the message is enabled...XIO MG.en...to keep it from firing continuous. It does no good besides filling up the buffers.

Not sure this is your problem, but it will probably cause problems with the buffers.

How many Ethernet messages are you executing? 4?

curlyandshemp · Sep 30, 2008

you are hammering the comm port hard until a buffer queue full error occurs that can only be solved by cycling the power to the plc.

manage the comms as an example such as this way. Only during a certain time slice will a message be triggered

alex08 · Oct 1, 2008

Thank you guys...

I'll test some changes in the logic and I'll post any advance of this topic...

Regards!

alex08 · Oct 15, 2008

Hi, I try to solve the problem restricting the messages when I dont need the results from DVT system, and also I include a timer in the logic to trigger each message only during a certain time slice, and I still having the same problem. Here is part of the last version of the program. Any other idea to solve this?

curlyandshemp · Oct 15, 2008

try the message isntruction without the unlatch after each MSG. Unlatching the bit will cause the MSG to execute as many times as possible during the 200ms each MSG is true. This is eventually causing a buffer overflow that can only be reset with a power off.

Also test the etherent cable between processors with an ethernet tester

Problems with SLC 5/05 MSG instruction over Ethernet communication

alex08

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widelto

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Sergei Troizky

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TimWilborne

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Oakley

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