Fieldbus has lost synchronicity

rmaas
2024-04-11
2024-11-10
  • rmaas - 2024-04-11

    Hi,

    On a gantry system with 2 axis i am getting the following error: SMC_DI_FIELDBUS_LOST_SYNCRONICITY

    This happens random, sometimes it happens every 5 minutes and sometimes no error for 2 hours...

    The Setup:
    - Using codesys 3.5 SP20 with all latest libs...
    - Kontron AL Pi-Tron CM4 with Preempt realtime patch (Raspberry Pi 4)
    - Codesys runtime 4.11.0.0 (single core)
    - CODESYS Control for Raspberry Pi SL licensed
    - Softmotion + CNC + Robotics licensed
    - 2x Leadshine EL8-EC400 servo drives
    - Axis group for a 2-axis T-Gantry

    Ethercat network wiring:
    Ethercat master softmotion -> Beckhoff EK1100 -> Servo drive #1 -> Servo drive #2

    Ethercat Cycle time = 4ms

    Max Jitter = 140~150

    What i have tried so far:
    - changed the sync offset from 20% to 30%
    - changed ethercat task priority from 1 to 0

    Running tasks:
    - Ethercat tast: Prio = 0, Interval = 4ms
    - Main task: Prio = 1, Interval = 8ms
    - Visu task: Prio = 31, Interval = 100ms
    - Softmotion planning task: Prio = 15, Freewheeling
    - 3 other default tasks that were created by AC_Persist

    Motion fb's are called in the ethercat task...

    Does anyone have an idea how to fix this? Any help is greatly appreciated!

     
  • tk096 - 2024-04-11

    Hi,

    a few suggestions on how to tackle the problem:
    - it might help to increase the cycle time of the ethercat task
    - increase the value of the ethercat parameter DCInSyncWindow (https://content.helpme-codesys.com/en/libs/IODrvEtherCATDriver/Current/pou-IoDrvEtherCAT/DCInSyncWindow.html) (see attached image)
    - enable FrameAtTaskStart (https://content.helpme-codesys.com/en/libs/IODrvEtherCATDriver/Current/pou-IoDrvEtherCAT/FrameAtTaskStart.html) in the ethercat master (see attached image)
    - if the drives can handle the synchronization problems, checking of the synchronization can be deactivated using SMC_Set_ETC_DCSyncSupervision (https://content.helpme-codesys.com/en/libs/SM3_Drive_ETC/Current/SMC_Set_ETC_DCSyncSupervision.html).

     
    πŸ‘
    1
  • rmaas - 2024-04-15

    Thanks for the suggestions!

    It seems that increasing the value DCInSyncWindow helped,
    running without error for 1/2 day now.

     

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