Hi there,

I'm trying to chase some sporadic USB faults with my smoothstepper driver on a large rack&pinion DIY gantry router table. VFD+ 2.2kw spindle

The problem seems to come from a new airblast system I've built using a fridge compressor, plastic airline and a welding nozzle...

The issue seems to get worse over several hours of use, at which point the USB driver will error within 5mins of a cut. The issue seems to go away when the air system is off..

It's electrically isolated from the rest of the system, sharing a ground at the compressor end, and the compressor runs continously. I will try a ferrite ring on the compressor power cable, but I'm wondering given the way it gets worse as time goes on, if it's static buildup at the nozzle? Would grounding the tip dissipate this do you think? I'm not sure if it's building up on the hose itself (which runs down the cable tracks with all the other sensor cables)

is an FT_IO_ERROR only caused by a problem between the smooth stepper and the PC - not by breakout issues? Is there any way of further diagnosing this? I have to disconnect the breakout AND pull the usb out to reset it....

Many Thanks,
James

The problem may be that after several hours of running continuously the fridge compressor motor is having a hard time and producing more electrical noise. Fridge compressors are not made to run continuously (they also need provisions for separating/recirculating the lubricating oil), they only run intermittently in typical use.

I have found that often a USB communication problem is not just a problem with the USB device but also the PC. Any electrical noise that feeds back into your AC lines can find its way back into the PC which can cause problems with the 5V power bus used by the USB ports). I've seen this in my shop when I turn on/off a florescent light above my workbench, the ballast is going bad in the fixture which causes enough noise to disrupt any USB device on the PC. If your keyboard or mouse are temporarily knocked out you will likely never notice but a motion control device getting cut off from the PC is another thing.

I added a line filter to the AC line before my PC: http://www.soigeneris.com/filters_and_ferrites-list.aspx (my website) there are also ferrites for power cords and USB cords there. This took care of most of the problem (as judged by looking at the AC line with an OScope.) Using an external power supply for the SmoothStepper also helped (have those on website as well). If you still have trouble then I would suggest a USB isolator: http://www.bb-elec.com/Products/USB-Connectivity/Isolators/Compact-USB-Port-Guardian.aspx . I have tested many of these units and found the ones made by B&B and Phidgets to work the best. Many of the other were next to useless.