VFD Control with 5i25 + 7i76

I'm close to finished with my scratch build milling machine and my final electrical item is getting the spindle running. I've got a Chinese VFD (brand is "BEST FC-300, 2.2kw") and while I've gotten it to run the spindle using its own control panel, I'm having trouble figuring out the interface with the 7i76, specifically in regards to the FWD/REV and Enable signaling. Hopefully someone here with experience can point me in the right direction.

The 7i76 has eight pins on the spindle TB (TB4):

Pin 1	:	Spindle-
Pin 2	:	Spindle Out
Pin 3	:	Spindle+
Pin 4	:	NC
Pin 5	:	Spindle ENA-
Pin 6	:	Spindle ENA+
Pin 7	:	Spindle DIR-
Pin 8	:	Spindle DIR+

Pins 1-3 have a clear explanation in the manual and I'm confident that they are wired to the VFD correctly using it's on-board 10v source.

What I'm struggling with is pins 5-8. I want to be able to switch the motor on and off in either forward or reverse. Normally I'd just use a multimeter to poke around and figure out what the pins are doing, but I've got a set of parallel questions around configuration of the spindle portion of my HAL file that makes me hesitant to rely on the current setup. I'd rather get the wiring nailed down correctly and then move on to figuring out the HAL portion (reduce my number of unknowns you might say).

Do I need to be using both DIR and both ENA pins to accomplish the control I want of the spindle, or are they just opposite polarities of the same signal? There's no ground on the TB, which makes me think they probably complete a circuit between (+) and (-) to indicate fwd/rev or start/stop. That would mean that I'd need a pair of relays to open/close the control circuits on the VFD. Is that correct?

My trouble is compounded by a poorly-written VFD manual. It can be found here. Section 2.4.2 is the portion relevant to this discussion.

To summarize my questions:
- Do I need to be using both DIR and both ENA pins to accomplish the control I want of the spindle, or are they just opposite polarities of the same signal?
- If they are just opposite polarities of the same signal, what should I use for common -- the field power ground?
- Do I need to use relays to control the spindle direction and enable?
- Does anyone have a wiring diagram from their own 7i76-powered machine that they can send over? Even if it's for a different VFD it would still be helpful.

Thanks in advance!
Henry