Does Linux CNC support Closed loop with Steppers?

jbraun wrote: The attempt to correct lost steps is done between the encoder and the drive. Linuxcnc is unaware of what happens there.
The shut-down alarm can be sent to Linuxcnc like an e-stop.

Correct and correct.
www.google.com/search?source=hp&ei=-r0ZY...WQBskQ4dUDCAY&uact=5

Thanks everyone,
This is very helpful. My stepper drivers have encoder inputs and alarm out if I understand correctly I should just wire the alarm out to Mesa board for LinuxCNC?
or am I misunderstanding and it would it be better to just wire the encoders to Masa directly and not the drivers?

Craig E wrote: Thanks everyone,
This is very helpful. My stepper drivers have encoder inputs and alarm out if I understand correctly I should just wire the alarm out to Mesa board for LinuxCNC?
or am I misunderstanding and it would it be better to just wire the encoders to Masa directly and not the drivers?

Your drive requires the encoders as you just mentioned. You cant just disconnect them from the drives and add them to linuxcnc.

Do what the guys are telling you. leave the encoders connected to the drives and alarm out to linuxcnc.

Craig E wrote: My stepper drivers have encoder inputs and alarm out if I understand correctly I should just wire the alarm out to Mesa board for LinuxCNC?

Yes, namely wire it to the "joint.N.amp−fault−in" as Rod mentioned in the hal file, but the actual wire from the fault output can be connected to any of the Mesa field inputs. It literally needs a single line added for each of the drive/motors used in hal.
Forget the encoders for now, leave them wired to the drive and let the drives do it's thing, first lets get the machine moving.

tommylight wrote: The only issue is when using closed loop stepper/drives and using the same encoders for LinuxCNC feedback ( even this will work for sure ) but might need some signal shaping and/or splitting to have the same encoder wired to two inputs on the drive and Mesa board.
.

This is something I have been looking into, my robot does this with its oem drives and has cables that go from the servodrives to the motion control card sending the encoder signals. So I have been looking for drives that do that aswell, and have found some of the lichuan drives do this servo.xlichuan.com/ProductsStd_212.html
Im not sure what the benefits would be for a cnc though with incremental encoder

Thanks everyone,
This has been a great help to me. Sorry if I ask any stupid questions. I starting from 0 knowledge. I just always wanted a CNC and I like building things. so I thought I would build a CNC what could go wrong?