Modicon PLC - OverRun Error

macs_plc

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Join Date
Jan 2008
Location
Nagercoil
Posts
120
Hi there....

I am getting the below error in Modicon PLC (Unity Pro XL), anyone has any idea to resolve this error....

Communication status on cable A
%SW538.1 = 1, overrun error

Communication status on cable B
%SW541.1 = 1, overrun error

Regards
Arvind....
 
Thanks for your reply...
nothing...No Visual indication...
We have ORed these error bits into HMI as a general Alarm, only the above said bits are active.....
 
Sorry ....I checked on the Remote IO Racks....I am getting many IO channel Errors in the Remote IO Racks.....
Is that may be a reason for the below error ? I can see the error description in the manual, but i couldn't gather any other details for solving this issue....Any help is appreciated...

Communication status on cable A
%SW538.1 = 1, overrun error

Communication status on cable B
%SW541.1 = 1, overrun error
 
Last edited:
The error on that card is most likely the cause, any idea what the error is? is it online and working? could be the addressing on rotary switches on the back of the card, if the card is not functioning.
 
Card termination are done correctly, RIO cards having some fault channels, but those channels are showing healthy in the PLC Logic processing, instead it shows "Overrun error" in PLC - ComA and ComB...
 
Are the line terminators fitted to each end of the RIO cables. The connection to the crp module (head module) must also be at the start of the bus
 
Brendonh....Fault channel indications in the RIO cards are because they were not connected to field, left as spares....all the other channels are healthy....

GeoffC....Gonna look at the terminator fittings....will be back....
 
Brendonh....Fault channel indications in the RIO cards are because they were not connected to field, left as spares....all the other channels are healthy....

GeoffC....Gonna look at the terminator fittings....will be back....

Having them as spare might be causing the overrun if they are configured on your head rack but the head rack cant communicate. As geoff says you may need to move your end terminators to where the last "active" card is.

just as a side note, i remember having to buy separate end terminators from schneider when i used coaxial remote io because i had problems with the standard terminators that came with the taps when using fiber repeaters.
 
The end terminators are connected in the Last active card...
I have checked the trunk cables and all the other connections including terminators, everything looks good.

We have configured/ORed this communication error words from %SW536 to %SW538 for Cable A, and %SW539 to %SW541 for Cable B into HMI, other than this overrun error Bits - %SW538.1 = 1 (Cable A) and %SW541.1 = 1 (Cable B) all the other bits are fine...

The system was working fine for last few months, this error popped up just before 1 week...

I would like to restart the system (or) Rebuild all project.....What is your opinion on this ?

Anymore Suggestions without restarting the system ?
 

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