Read encoder index using I/O

Hi Andy,
That certainly sounds like a plausible solution, if I was to utilise the leadshine drivers I wouldn't need differential inputs to the mesa hardware either as I could put an encoder splitter near the drivers and the cable length wouldn't be an issue any more. Ie differential from the encoders to the drivers and then single ended for the short run to the 7i76. I have, however, now ordered a 7i77 as it will be cheaper than replacing my drivers while also being possibly the more "correct" way of doing things.

Clarification of potential solutions:

1. Replace current drives (Kinco 2M2280N) with leadshine ES-DH2306 and install encoders on the steppers to feed A and B channels into the new drives. I was then interested in the possibility of feeding the index channels into the 7i76 for homing purposes. Doing things this way would allow me to leave my stepgen setup unaltered.

2. Buy a 7i77 and run all the encoder channels into it, either for full closed loop operation or for monitoring following error. This allows me to keep the dumb kinco drives but if I go down the closed loop road requires modifying my stepgen setup.

Where I have mentioned previously running in velocity mode I was referring to the stepgen, not analogue output. I hope that answers your question otherwise maybe you've spotted something I have overlooked?
I would like to get to the stage whereby my gantry squares itself using the index pulses and monitors it's position while working to ensure it may be left unattended; while also having Rob's new trajectory planner. However it seems DaBit has done some work towards achieving the same goal without obtaining a satisfactory solution (from threads you were very active in Andy). Before I read that thread I was under the impression that gentrivkins would solve my problems but it seems further digging is required.

Thread referred to in post: linuxcnc.org/index.php/english/forum/49-...try-machine?start=20

Haha yes another thing didn't mention! The 7i77 will be running off the P2 connector from the 5i25 alongside my 7i76 on the P3.

Did you need the additional IO or the analog outputs for somthing? I would have thought that a 7i85 or 7i85S would have been a more economical way to add encoder inputs.

This machine may end up with 5 encoders on it in which case the 7i85 wouldn't have enough inputs. Also mesa supplies a pre made configuration for a combination of 7i76 and 7i77, nice and easy in pncconf then!

Don't forget the 7i76 has one of it's own.

Oh yes, never mind I'm sure I'll have a play with servos someday and I'll be glad of the 7i77 then.