Hey, We have a UR10e running a machine tending application. The machine is connected to a Siemens LOGO V8.2 plc. For some reason it started losing its connection after 3 months of running without issue.
The exacted error is “MODBUS Signal [xxxx] is not connected to slave.”
This is a program warning so it just gives me a default error code C0A0:10 in de logs. (not helpfull)
The error accures every 2 to 7 days. Off course all in the night hours. I cant find a mechanical fault with it so i think its a software problem. Im checking and setting about 20 boolean signals at 25hz.
Troubleschouting steps taken.
-checking earthing of machine and kabels
-checking connections of kabels (switched to different kabel at this point)
-removed intermedian devices from network (made direct connection between cobot and PLC, no switches)
-turned of sequentialmode (still testing that one)
The signals arent time critical so the frequenty can go as low as 5Hz .(next step to try)
I could also write a script to check if the signal is online. if it is it check and sets the signals. if its not is restarts or waits for the connection. But thats a bit overkill as the system should do that automaticly. (but its doesnt so no overkill)
Anyone have any other ideas or suggestions for sollutions?
Probably not too helpful for you, but we’ve had a similar problem with a handful of the robots we have in one area.
These all use Acromag I/O devices to handle some communications and triggers.
We’ll go quite a while with no issue, then get the same error message.
Our assumption is that our network has a temporary glitch, which causes the Acromag to fail. These devices don’t seem to be very good at reconnecting after a communications loss, which would explain why those devices show an error while none of the other network connected devices have an issue.
Clearing the error requires a hard reset of the power circuit with the Acromag unit.
We’ve tried tracking this down to try to get a better idea of what’s happening - Our IT group was tracking those IP addresses at one point, but I would have to get a call from the operator to tell me when they saw an issue, then reach out to the IT group with that info, then often wait a day or two (or more) for any feedback from them as to whether they saw anything from their end - it was unwieldy enough that we haven’t really followed up.
I haven’t heard anything from the operators for several months - this could mean they haven’t had problems, or that they have given up mentioning it and just restart whenever it happens.
I would recommend always using sequential mode. It’s probably a noisy network (modbus/tcp is not very robust when it comes to handling dropped packets). There are some urscript functions in the latest version of polyscope (~5.15 or so) that allow you to monitor for errors are restart. Search in script manual for these.