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Author Topic: Nema motors not responding - PMDX-424  (Read 342 times)

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Nema motors not responding - PMDX-424
« on: June 03, 2022, 03:48:40 AM »
I have a new Mach4 install and a scratch build CNC using PMDX-424 controller. I cannot get the Nema34 steppers to react to input from Mach4.

I’ve gone through an extensive troubleshooting exercise and found the following.

All motors and motor drivers are connected as follows and seem to be correct from digging around several forums.

I’ve tested the Nema34 mutator cables (LED test) and have the correct pairs connected to the “A” and “B” terminals on the motor drivers. Also, I have 60v into the motor drivers.

As an additional test, I did change the polarity on the “B” coils to check if they don’t oppose the “A” coils causing the motors not to run. This provided the exact same result and I swapped them back

The connection from the motor driver to the PMDX-424 is connected like this…
On the motor driver side, PUL+(+5v) and DIR+(+5) are bridged then

Driver side   -   SB424 side
PUL+(+5v)   -   COM
PUL-(PUL)   -   STEP
DIR-(DIR)   -   DIR

I have a5v from the controller board to the drivers on a separate lead pair connected to +ENBL and -ENBL from the J12 connector on the PMDX.

The controller PC runs Windows 10 and I have the latest USB drivers (0.53.263) and PMDX firmware (0.60.208) loaded. The respective plugins are enabled and the correct controller is selected in the Mach4 software.

RED and GREEN LEDs light up as expected. DS4 light up when I "enable" the Mach 4 and DS3 fishes when I press the JOG buttons.

I’ve opened the PMDX-424 real-time debug tool and see the pulses and directional indicators flash as I press the jog buttons. This coincides with the DS3 LED on the board.

The only reaction I do get from the motors is the sound of them demagnetising (I think) when I power the system down.

I see some errors on Mach4 from time to time...
1.   PMDX: No synchronised position from motion planner
2.   PMDX: DEVICE ERROR “SYSTEM ERROR(7): Motion underrun
3.   Line 0: Axis 3 commanded while disabled

I am at a dead end and do not know what else to check.