Using Pixhawk with RoboteQ Motor Controller

If I were building an aerial drone (UAV) I would not be asking this question …
However, this special project is an overside UGV and can not figure how to connect my Pixhawk via the RoboteQ motor controller.

So I figured I would ask the group if anyone has tied their Rx, Pixhawk, to a RoboteQ MDC2460 together with success?
The motors connect to the motor controller (MDC2460) to Rx module (RC2) via RS232 cable.
The RC2 allows digital communications between the MDC 2460 to operate the motors using an Rx.

With this device I can operate both motors (48vdc) fwd and rev without any issues.
However, I plan on using the Pixhawk for various waypoints and do not have any ESC’s or PDB (power distribution board) attached to the Pixhawk. I have tried connecting directly to the Pixhawk to the RC2 and does not provide a signal to the MDC2460 motor controller.

I have tried researching information till my eyes turned cross looking at all of this.

Again I’m trying to get set up to using waypoints via Pixhawk with my Rx but the motors will not operate (either direction) when I connect them directly to the Pixhawk - but - connected at the Rx the motors operate but then the Pixhawk cannot provide motor operation for my waypoints.

Any help would be appreciated.
Thanks