Relay Wiring Question

Hello Fellas,
I feel so stupid asking but…, Im connecting my X-Controller to my VFD and Ive run into an obstacle that is tripping me up. Ive read through the numerous posts related to this upgrade, I have the correct relay, but the relay has 3 input pins. Signal, +, and - . I understand I need to connect M8 and ground to this side of the relay and Grd from the X-Controller goes to - but which connection does M8 go to? I assume Signal but then does + stay open or do I run 5v from somewhere else on the X-Controller?
Thanks, Mike

I know right, a real stumper. So I grew impatient last night and took the damn thing over to the test bench. If I go ground to ground, 5v across both + and Signal the relay works.
I dont know if that is the correct way of wiring it in but its the only way it works.