Profinet connection failure

    We are getting a PRIO-379 PRIO Chnl 2 Slot 1 idle intermittently on one of our lines. When this happens the effected robots slow down to 10%.
    Fanuc says the PLC is the cause and our PLC guy says it's the robots. Not all robots are effected when this happens and that leads me to believe it isn't the PLC. Has anyone else had this alarm and if so what did you do to remedy it?

    Sounds like PN comms loss, maybe a bad cable? Or ive seen slow plc scan times create delays in rpi. If your speed override is active and both signals off = 10% then that would explain the slowdown. What plc is running? And what is the overall scantime?

    Siemens S7300 series.
    Scan times to the robots is 2ms.
    What do you mean speed overide is active?
    I don't think it is a bad cable because multiple robots are on the same switch and only one will fail.
    The alarm is very intermittent, occuring once every couple of months.


    I believe he is referring to the speed override variable on the TP for the robot. Whenever power is cycled the robot speed will drop down to a safety speed of 10%. Ours are all set to return to 100% override speed for this reason.

    "I could tell that my parents hated me. My bath toys were a toaster and a radio."

    Actually i was referring to the override select shown in attached pic. Menu/setup/ovrd select. You can assign DI's from the plc over profinet to allow the plc to control the override speed. Normally values for fieldbus I/O default to zero when disconnected or comms lost. So if you had DI 1 & 3 in my example both on the robot would run at 100% but if u lost comms the override select would interpret it as a request to run at 10%.

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