Error Light double flash


We have set up 2 bytes in and 2 bytes out (status and control words) when we download the configuration the run light is on but the error is giving 2 flashes. A nodeguard event or a heartbeat event has occurred. I have looked in the drive and can see the 500ms heartbeat signal, if the time for this is changed it also changes in the drive. Is there any way I can confirm it is a node guarding causing the issue and not a heartbeat issue


Hello Cole,

What device are you working with is this the CM CANOpen module?


I was wondering how it was solved.

I have the same issue with SICK MLSE-0300 (Line guidance).

Iā€™m using S7-1212. I read data from the sensor but after each 2 seconds perfect transmision there is 1 second break (no data arrive to PLC). (Some bus or sensor reset?)

I looked on CAN bus using USB converter but MLSE transmitting well (conection MLSE to PC).

Where I should look a problem? In S7-1200 configuration, MLSE configuration or CM CANopen Studio?

I solved this problem: bad CM CANopen / MLSE configuration of heartbeat.

In MLSE sensor heartbeat was set to 250ms and in CANopen Studio was the same.
But I think CANopen Studio still took value of heartbeat from factory settings (library).
I changed both in sensor and in Studio to 500ms (default factory value) and now everything working perfect.

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