I have a Mach3 / SmoothStepper USB freeze / lock up problem.

I have a home build system and are still trying to configure it. The main components consist of a Sieg X2 mill, Stepper motors, Gecko G540 controller, SmoothStepper USB, laptop running

Windows 8 using SmoothStepper's Windows 8 drivers.

I first connected a D9 socket directly to the ends of the stepper motor cables (about 30cm) and connected this to the G540's x-axis port.

This worked fine and I could tune the motors and played with this setup for about 30 minutes.

I then added a standard serial port cable (about 1.8m). This works randomly from 2-30 seconds and then cause SmoothStepper / Mach 3 to lock up. When locked up, SS still have the green

and blued LEDs on solid, but the red heartbeat LED stops flickering and is off.

I think it is the SS board and not Mach 3 becuase I can close and reopen Mach 3 and it will still be broken. But when I close Mach 3, and unplug and reinsert the USB cable (essentially

cutting the SS board's power supply) it works again when I start Mach 3 up.

So my question is: Why should this setup work perfectly for a short stepper motor cable, but fails when I add an extension?

What I have tried up to now is:
1. Tried an older Windows XP 32-bit laptop.
2. Different combinations of grounded / floating USB / SMoothstepper ground relative to controller box and G540 board.
3. Removed the SS board competely from the controller box to put it in a less noisy environment.
4. Configured noise filters on SS configuration in Mach 3.
All with the same result.

I have a multimeter and oscilloscope available for testing if anyone has some theories to test. I also tried configuring SS diagnostics logging, but couldn't figure out if / where logs

are created.

Any suggestions would be welcome. I am really frustrated with just looking at my machine after weeks of hardware kit upgrades and now not being able to even move 1 axis from the PC.

I see a couple of issues here:

1) You cannot use a DB9 serial cable as a stepper cable. A typical serial cable is made from 28~30AWG wire which is much too small to carry the current needed for stepper motors. You need at least a 22AWG cable, I like to use 20AWG wire when building G540 cables as it is a bit more robust. Take a look at: http://www.soigeneris.com/custom_made_g540_stepper_cables-details.aspx for custom made G540 cables. (my web site)

2) I suspect that since you have a DB9 on your motor that you have one of those motors where they put the G540 current programming resistor in the connector on the motor. Gecko DOES NOT recommend this as it is a really, really bad idea. The current programming circuit is a low voltage analog circuit. If the current programming resistor is at the motor that means you are running the two wires for the resistor all the way to the motor and back. This will let electrical interference from the high voltage stepper motor wires into the current programming circuit and the G540 will not work properly.

I would suggest making or buying some proper stepper cables and moving the current programming resistor to the G540 end of the cable where it belongs. If you want to order some custom made cables I can put a DB9 on both ends so they will plug into your motors but will put the current programming resistor at the G540 end (suggest getting EZ-G540 option.)

Also, with USB it is possible to overwhelm the USB connection with electrical noise. Don't run the USE cable along with the stepper cables and use a separate 5V power supply for the SmoothStepper: http://www.soigeneris.com/meanwell_ps_05_power_supplies-details.aspx . I have seen many a USB device not work properly because the PC can't put out enough current on the USB port. Using a separate power supply solves many problems.

Thanks for the information Jeff.

This is what I have found:
1. Switched to 22AWG cables. Good idea, since it should handle the current better. But it did not improve the SmoothStepper hanging up.

2. Moved the resistor to the G540 side of the cable. SmoothStepper still hanging up.

3. Use an external 5V power source for SmoothStepper. This improved things a lot, but I still got lock ups once in a while.

4. Bought an old desktop PC and use the parallel port directly to the G540. Throw out the SmoothStepper. Couple of hours of testing later I had no problems.

Conclusion: I thought I would save a couple of $$ by using my existing laptop and adding the SmoothStepper interface in between, but the money would have been better spend going straight for the desktop PC.