NEURON THC - Proper connection to optocoupler inputs; Incorrect connection to optocoupler inputs sample; Set JP1, JP2 jumpers to 1-2 pins for differential connection:

USER MANUAL
In this case, we do not use twisted cable and that is why the connection is more exposed to
the influence of interferences.
It is important to do not connect STEP- and DIR- pins with GND of the device because it
will cause short circuit and output stages damage.
THC kit has a special adapter PCB for connecting Neuron differential Pulse/Dir output to the
motor driver.
Set JP1, JP2 jumpers to 1-2 pins for differential connection: