7i76E + Rotary encoders.

I have been fiddling with this ethernet card for stepper motors and trying to figure out if i could wire in rotary encoders for a feedback loop to it.. Or well i guess it can be done - but not figured out how yet. I bought Omron 2000ppr encoders off of ebay (seems to be some chinese 5V clones / OMRON E6B2-CWZ1X).

Anyone done this before and could point me in the right direction?

I think would be best to add another card such as a 7i85 to read the encoders. But if the encoders can be connected for a single ended ttl signal, you might be able to connect them directly to the extra pin headers. That is a little riskier though as there is little protection for the card in case of a wiring problem. Regardless you will probably have to re-flash the firmware for the card to add the encoders. Hopefully Peter will weigh in with the exact details you need for that.

I have to ask though what you hope to accomplish, as closing the loop with ordinary steppers in Linuxcnc doesn't seem to be very practical. Unless you only hope to cause a following error shutdown, if the error becomes too large.

I have fiddled with Steppers + Rotarys on a Kmotion board before. And yes it error shutdown is one thing. But repeatbility was the major advantage i got out of it. Just way more precise positioning and still be able to run really high speeds on the steppers. In that case a laser.. In this case a plasma just chasing precision i guess.