The PMDX-424 can drive the step and direction inputs of the ClearPath drives.
The issue for the HLFB signal from the ClearPath drives is that it is inverted
from what we would like to see. The HLFB output conducts when it is happy
and goes open when it detects a fault.
If you can combine the HLFB signals into one signal that conducts when the
drive is NOT happy, then that can be connected between the /Fault and GND
pins of J14 on the PMDX-424. This will report an E-Stop to Mach4 when the
drive is not happy and no script is needed. This can probably be done by
wiring the HLFB signals in series and driving a relay that is small enough
not to exceed the current limit of the HLFB signal. I could not find where
they specify the maximum current for the HLFB signal by my guess is that
it is around 25 mA. Be sure to put a clamp diode across the relay coil to
absorb the inductive kick when it turns off.
If you wish to avoid additional circuitry, then you would need to connect
each drive's HLFB signal to an individual input on the PMDX-424 and run
a script to monitor the signals.
Wiring the HLFB signals from several drives in series will probably result
in too much voltage loss to combine them in this was for feeding into one
of the PMDX-424 inputs, but you can try it. This signal is still inverted
from what the /Fault input wants to see, so you would still need to run
it to a regular input and run a script.
