AB messaging stopped working

Chris_M · Mar 7, 2023

I have several AB 1769's that transmit messages to each other.

Sometime last night/this morning one of the messages stopped transmitting. It is not an issue with the PLC or network as I am able to connect and there are other messages on the PLC that are working.

I am using CIP Data Table Write

The "Enable" Radio button was lit and there was no error code/ text/ path.

I had this happen before and my work-around was to message to another PLC and use that PLC to write to the intended recipient.
Is there a way to reset the message tag when this happens again?
Some way of detecting these communication breaks?
Thanks.

Operaghost · Mar 7, 2023

One of the issues with the logic often used to trigger messages is that they are programmed to keep repeating the message over and over. And when that happens, you sometimes don't get a chance to see the Error (ER) bit coming on. The message just re-triggers and the ER bit is cleared. Perhaps though the error message/code is still available.

When looking at the MSG in the logic, click on the ellipsis button (the button with three dots). In the Message Configuration window down at the bottom you would hopefully be able to see the status of the message along with an Error Code and an Extended Error Code.

Knowing these codes could help us sort out the problem and how to recover.

OG

Jim3846 · Mar 7, 2023

Make an alarm or fault for if the enable bit is on too long with a ton, then set a latch bit. and if the error bit is set with a ton , then latch a bit.

There is a cache connection check box if you want the connection to stay open. Check that so that it does not have to open the connection repeatedly.

Chris_M · Mar 8, 2023

Operaghost said:
One of the issues with the logic often used to trigger messages is that they are programmed to keep repeating the message over and over.
...
Knowing these codes could help us sort out the problem and how to recover.
OG

I'm using a timer to send the message every 5 seconds. There was no error message in the configuration and no error codes to report.

Jim3846 said:
Make an alarm or fault for if the enable bit is on too long with a ton, then set a latch bit. and if the error bit is set with a ton , then latch a bit.

There is a cache connection check box if you want the connection to stay open. Check that so that it does not have to open the connection repeatedly.

Cache connections is set. The EN timer is a good idea I will look into that.

IO_Rack · Mar 8, 2023

Chris_M said:
I am using CIP Data Table Write

Chris_M said:
There was no error message in the configuration and no error codes to report.

I would change this to a READ from the other end.

JeremyM · Mar 8, 2023

What does your message triggering code look like?

Chris_M · Mar 8, 2023

jeremym said:
what does your message triggering code look like?

                 timer



------------------ton--





timer.dn



--][--------------msg--





timer.dn      timer.res



--][-------------()--

About like that, the timer runs 4 or 5 messages.

JeremyM · Mar 8, 2023

Use this instead:

Code:

XIO Timer.DN TON
XIC Timer.DN XIO Msg.EN Msg

This guarantees the Message is ready to be run and has no outstanding resource allocations from previous attempts (waiting for timeout, and so on). You can follow up with more rungs to get message diagnostic data but this is the simplest way to do messaging 100% reliably.

Chris_M · Mar 9, 2023

JeremyM said:
Use this instead:

Code:

XIO Timer.DN TON XIC Timer.DN XIO Msg.EN Msg

This guarantees the Message is ready to be run and has no outstanding resource allocations from previous attempts (waiting for timeout, and so on). You can follow up with more rungs to get message diagnostic data but this is the simplest way to do messaging 100% reliably.

Thanks, will do.

AB messaging stopped working

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