The setup is simple, but we really should add this to the PMDX-407 information.
The Com on J2 of the PMDX-407 should connect to the Common of your VFD
interface. If you have the VFD working now, you have already done this.
The Run on J2 of the PMDX-407 should connect to the relay Com on J18 of
the PMDX-424 (or the Com terminal of any SmartBOB with a relay of any
external relay that you may add).
Connect the relay N/C on J18 of the PMDX-424 to the FWD input on your VFD.
Connect the relay N/O on J19 of the PMDX-424 to the REV input on your VFD.
Configure Mach4 to use the "Spindle Rev" output signal to control the relay.
You will find this near the bottom of the list of signals here:
Configure > Mach > Output Signals
The Enable column should have a green check mark.
The Device column should be set for your SmartBOB device.
The Output Name column should be set to Relay (or other pin name
if you happen to be using an external relay that you have added).
The output name Relay will not appear in the list if you have any
other output set to use that output name.
The Active Low column should have a red X unless you have the FWD
and REV swapped in your wiring.
There is no need to configure the Spindle Fwd or Spindle On signals.
The SmartBOB plugin is receiving these signals directly from the
Mach4 software API.