Watchdog misbehavior

8 months 6 days ago - 8 months 6 days ago #29535325 by ljmp
Watchdog misbehavior was created by ljmp
Hi.

Im using GIM2660 to drive 1000kg vehicle with two 3kW motors in FOC Torque Mode. Command signal is given via RS232. Command safety is provided by watchdog configured to 1000ms. The manual says "Watchdog for automatic motor shutdown in case of command loss" but when command is lost there isn't anything like automatic shutdown. What i get is instant brake to 0 and all the drive and mechanisms want to fall apart because of big jerk. For me it does not look like motor is shut down but its like pwm is reduced to 0 hence the big jerk appears, please notice i said "PWM reduced to 0" not "setpoint reduced to 0", if setpoint would be reduced to 0 then motor would stop by coasting. This is dangerous for people staying in the vehicle, its damaging to gearboxes and whole drive. Please help me to find solution.

Best Regards.

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7 months 4 weeks ago #29535333 by LROBBINS
Replied by LROBBINS on topic Watchdog misbehavior
You can get a more gentle watchdog response if you script your own watchdog handler.  I do so in my CANbus system like this:

DIM CANwatchdog as INTEGER 'msecs for timer 0
CANwatchdog = 100
SetTimerCount(0, CANwatchdog) 'reset CANwatchdog each time joystick message received
SetTimerState(0, 0) 'start timer

  GoSub RECEIVE_MESSAGE 'Timer 0 is reset and re-started if a joystick message is received; joystick messages are sent every 50msec or less.
  IF (GetTimerState(0)=1) THEN 'set Throttle and Steering to 0 if CANwatchdog has timed out
    Dropouts = Dropouts + 1
    IF Dropouts >= 2 THEN 'avoid triggering stop if just 1 message gets lost
       Throttle = 0 'Throttle and Steering are eventually used as _GO values
        Steering = 0
    END IF
  ELSE
    Dropouts = 0
  END IF

 

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