My cnc router was working well, when I started getting error messages. Smoothstepper is used.

Error message is:

Error returned from USB function FT_Write
Error: FTDI USB driver error

ERROR= FT_INVALID_HANDLE

Bytes requested 64
Bytes written 26

Any suggestions for fixing this?

Red led remains lit on smooth stepper

Thanks,
Jim

do you have a pokeys connected too. i have problems with the combination of ESS and PokeysUSB

I get the same error message , it started when I switched to a usb controller board. don't know why it does it but I wish it would stop.

You have a ground loop issue on the 5v supply to the USS, have a look at the info on the warp9 website and forum, plus ask on the forum as it is better supported by the manufacturer