7i96 MPG Encoder A- B-

New to LinuxCNC - I added an MPG to the Spindle Encoder of Mesa 7i96.  Initially I had only A+ B+ 5V GND on TB2 Connector and it was having trouble moving and was registering only 1 count in Hal.  Going thru the forum comments, I removed the 5V from TB2 and connected it to the main 5V supply.  I was able to move the axis and able see the counts.  However it would not reverse, so i connected the A- B- and it started working both forward and reverse.

Any reason, I need to connect the A-B-? because the posts mention A+ B+.  The TB2 provides only 4.4V and my MPG says 5V-15V could that be a reason for not able to use the TB2 5V?

Thanks
babu

If you have differential outputs (A+,A- ,B+,B-for example)
you should jumper the 7I96 encoder inputs to differential mode
and use all 6 wires.

If you want to use single ended mode (only A+,B+)
you need to jumper the 7I96 encoder input for single
ended mode.

Thanks that worked, also the +5V GND on the encoder section also works. No need to provide separate power to MPG.

thanks