Need help understanding Rotary encoder.

Hi!

I'm adding a Poorman's Smart LCD controller. Basically wired a 2004 LCD, SD card reader and Rotary encoder to a RAMPS 1.4 (About $8). I do have the pinouts from the RAMPS 1.4 (Marlin). I hooked up the SD, am waiting for my LCD to arrive. I have this Encoder:



I'm not sure about the Encoder.

I found this diagram:



Do I understand correctly, the side with the 3 pins, is the encoder, the two pins on the opposite side are the switch.

1) I need to wire to the RAMPS:

BTN_EN1 pin 31
BTN_EN2 pin 33
BTN_ENC pin 35

Am I correct, the two outer pins on the 3 pin side, are EN1 and EN2? How do I know which is which? The center goes to ground?

2) On the switch side, one pin goes to BTN_ENC pin 35, the other to ground. Again does it matter which pin goes to ground of the two?

Finally, to save wiring, can the two "ground" pins on the encoder be wired together and only one jumper to RAMPS ground?

Thanks.

Getting closer!

Maxi