1A, 1B and 1I are inputs 1,2 and 3 on Port3
2A+, 2B+ and 2I+ are inputs 4,5 and 6
2A- 2B- and 2C- are only used if you are connecting a differential encoder or Differential MPG to Port 3. A differential encoder will have A+ A- B+ B- I+ I-, a single ended encoder will only have A B and I
So if your MPG is single ended you just connect to 1A and 1B and then in ports and Pins, MPG page set it up as Port3 Pin1 for A and Port3 Pin2 for B.
Hood