Motor not moving troubleshooting

This article lists common reasons for motor not producing desired motion when using GD motor drives.

The suggested actions are described for drives supporting Granity software. Hoever similar instructions apply to older GDtool based drives too.

List of reasons

Fault state of drive

Drive suspends all motor control until fault is cleared. If fault occurs again, check parameterization of drive or try adjusting fault tolerance limits to higher. If no stability can be achieved, pay attention to correctness of motor parameters MPC, FBR, FBI and FBH. In many cases counting direction of encoder is opposite of assumed, so inverting FBI setting may be needed. All of these settings safe to experiment if motor is shaft unmounted.

Incorrect motor settings

Double check all motor parameters especially on Machine tab of Granity. Also see the previous paragraph ↑↑.

No setpoint signal

Try moving motor by giving commands Granity's Set Abs and Set Inc buttons. If motion is produced, then check correct setpoint source settings, wiring and phyiscal presence of proper signal.

Output current is insufficient to overcome load friction or weight

Try increasing motor current limits or try motor without any load

No current flow on motor

Verify that current really flows through motor by doing response tests at Granity Testing page. Tick Torque setpoint & achieved signals to see the target current and actual current of motor. Both curves should stay close to each other. If Torque achieved lags significantly behind, it is sign of insuffucient supply voltage to overcome motor coil resistance or EMF. One possibility is also activation of STO that forces drive power stage off. Also check motor connection and measure the resistance of motor to see if it appears as proper electrical load (make sure to follow Power supply safe discharging if measuring resistance while motor is connected to drive).

Motor initialization has failed

If Hall sensonrs (FBH) are not used, then drive may fail to initialize motor properly under significant mechanical load or due to weight of vertical axis. Try increasing current limits or connecting Hall sensors (if motor is equipped with them).

AC/BLDC/Linear motor locks up when it is supposed to rotate or generate torque

You can verify this condition by setting drive in torque mode and setting non-zero torque command (like 10-30% of motor rated torque) and rotating motor shaft by hand. If you feel motor is holding still and with some force you can make it jump/stop to another position, then the reason is invalid motor configuration parameters or an issue with position feedback device. Check following settings for correctness (all of them must be exactly correctly set to avoid this problem):

• Invert feedback direction FBI - try inverting this setting
• Feedback device resolution FBR - also verify it by inspecting at Position feedback reading on Testing page while rotate motor by one turn. FBR value should be 1/4 of the total change of position counter during one rotation.
• Motor pole count MPC - if unsure, see Determining motor pole count page
• Hall sensors not properly functioning - try FBH setting Off

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