CM Can Open, Transparent Can, sometimes works sometimes it doesn't

Ixxat Support CAN/CANOpen PLC Extensions
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#1

Hello,
I’m implementing CAN into my PLC program and i have several issues:

  1. The Can comunication someties works sometimes it doesnt. It sometimes without any regularity either doesnt send CAN message or recives one. I dont know why this happens i will include screenshots of my device configuration and ladder blocks at the end.
  2. After few attempts of fixing the problem 1. , the CAN comunication stoped working at all. I recive nothing and can’t send anything, addictionaly when i connected logic analyzer and then the CM module to the CAN network, it stops working (the signals from other devices disappears), and i cant get it to work like before. I checked the cables and the plug it has correct conections and nothing is broken in them, i even changed the cables to be sure.

I include the screenshots of my program:

I’m using PLC Simens 1215C DC/DC/DC

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#2

Intermittent problems are most likely caused by physical issues on the CAN bus. I would recommend checking the electrical properties of the bus. Do you have termination resistors installed?

#3

Yes 120 ohm on each device. And i checked the cables with
electric meter and everything works.

#4

Since this is a fairly complicated problem, I would recommend creating a case at support.hms-networks.com so it can be escalated to the IXXAT engineers to take a look at.

Please send them your configuration and a CAN trace if possible.