Steppers not moving, 7i96

Update, the stepper motors seem to hold position just fine and step when given a +5V pulse from a separate power supply.

It might be that the 7I96 step output driver chips have been damaged.

A quick test is to measure the STEP+ and STEP- pin voltage to ground

1. When LinuxCNC is not running
2. When LinuxCNC is running

They should be  close to 0V or close to 5V and change state
depending on whether LinuxCNC is running or not.