Documentation

MASSO Closed Loop Stepper Troubleshooting

MASSO closed loop stepper status LEDs

How to diagnose alarms on MASSO closed loop stepper motors, by what you see on the motor's red LED and on MASSO.

1. Red LED permanently on

The red LED stays on when the motor loses steps and can't recover – for example because there isn't enough power to drive it, or the pulse rate is higher than the motor can process. Repowering the motor clears the alarm.

If repowering doesn't clear it, check the enable signal:

With a multimeter, measure between the motor negative and the motor's EN input.

You should read 5–24 V. If not, look for a broken wire.

INFORMATION

The only requirement to clear the alarm LED at power-up is that the enable signal is present.

2. Alarm on MASSO, but no LED on the motor

Check the motor alarm input on the F1-Setup screen. It must not be inverted, and must read Low when the motor shows no alarm.

Situation	Check
Input reads High, no LED on motor	The AL wire between motor and MASSO. The input is fail-safe, so a broken wire makes it read High.
New installation	The 10K resistor is fitted, and the motor supply negative is connected to the MASSO supply negative.

3. Flashing red LED

When the drive detects a fault, the red LED flashes a number of times (0.8 s per flash), pauses for 2 s, then repeats. Count the flashes:

Flashes	Alarm
1	Motor coil current exceeded the drive current limit
2	Voltage reference error in the drive
3	Parameter upload error in the drive
4	Input voltage exceeded the drive voltage limit
5	Position following error exceeded the limit

General checks:

All wiring is secure and correctly connected.
Speed and acceleration aren't too aggressive – reduce the speed or lengthen the acceleration time.
The axis isn't binding, which can stall the motor.

Five flashes at power-up

If the motor moves during power-up – most often a Z axis dropping – it alarms with five flashes. Only power cycling the motor clears it: turn the machine off and on, or power cycle the motor alone. Cycling E-Stop can make the motor rotate and alarm again.

TIP

Release the E-Stop button before powering up the machine.