10.2 Warning Displays10-2110 Troubleshooting10.2.2 Troubleshooting of WarningsRefer to the following table to identity the cause of a warning and the action to be taken. Contact yourYaskawa representative if the problem cannot be solved by the described corrective action.WarningDisplay Warning Name Situation at WarningOccurrence Cause Corrective ActionsA.900 Position ErrorPulse OverflowWiring of the servomo-tor U, V, or W line isincorrect.Check the wiring of the cable formotor main circuit.Check whether there is any loose con-nection in motor wiring or encoderwiring.The SERVOPACK gainis too low. Check the SERVOPACK gain. Increase the servo gain by using thefunction such as advanced autotuning.The position referencepulse frequency is toohigh.Lower the position reference pulsefrequency.Lower the position reference pulsefrequency or the position referenceacceleration, or correct the electronicgear ratio.The position referenceacceleration is too high.Lower the position reference accelera-tion.Apply a smoothing function, such as aposition reference acceleration/decel-eration time constant (Pn216).The excessive positionerror alarm level(Pn520) is too low forthe operating condi-tions.Check the excessive position erroralarm level (Pn520).Set an appropriate value for thePn520.A SERVOPACK faultoccurred. −Turn the power supply OFF and thenON again. If the alarm still occurs, theSERVOPACK may be faulty. Replacethe SERVOPACK.A.901Position ErrorPulse OverflowAlarm at ServoONWhen the /S_ON signalwas OFF, the servomo-tor moved withoutcleaning the counter forposition error pulses.The number of positionerror pulses exceededthe maximum numberof pulses allowed.−Set Pn200.2 to 0 to clear the numberof position error pulses when the/S_ON signal is OFF. Or set an appro-priate value for the excessive positionerror warning level at servo ON(Pn528) when the /S_ON signal isON.A.910Overload:Warning beforealarm A710 orA720 occursThe servomotor orencoder wiring is incor-rect or the connection isfaulty.Check the wiring. Correct the servomotor and encoderwiring if they are wrong.The servomotor is inexcess of the overloadprotective characteris-tics.Check the overload characteristics ofthe servomotor and reference input.Reconsider the load and operationconditions.Or, check the servomotor capacity.The servomotor is notdriven due to a mechan-ical factor and the oper-ating load has becomeexcessive.Check the reference input and motorspeed. Improve the mechanical factor.A SERVOPACK faultoccurred. − The SERVOPACK may be faulty.Replace the SERVOPACK.
