can linuxcnc use easson dro for feedback?

Hi, I have been reading the mail for a while but this is my first post on the forum.

I am trying to decide whether to use steppers or servo's on my mill when I put ball screws on later this year, so I would like to know if linuxcnc can use the signals from the easson dro as position feedback? It would seem a shame to have very accurate position information there and not use it.

If it can then I would guess servo's would be the way to go, but being a complete novice at this, I need all the advice I can get. Price is a big consideration- being retired, there's not a lot of money to throw around- but there is a lot of time available!

I tried searching the forum, but came up blank- though I find it hard to believe that the word "easson" doesn't appear anywhere in nearly 60,000 posts?

Ken.

Hi

I tried searching the forum, but came up blank- though I find it hard to believe that the word "easson" doesn't appear anywhere in nearly 60,000 posts?

I had never heard of Easson before. Newall, Accurite, Mitutoyo etc but not them
However appears a lot of UK stockists now sell their scales and complete kits

The important thing to know about your Easson scales is that they are glass scales outputting a 5 volt TTL Quadrature signal

With that knowledge, there is a post of quite recently that should help you
www.linuxcnc.org/index.php/english/forum...cales?start=20#53438

regards

yes you can they ( scales ) output quadrature , see attached pic , but beware i have known different pinouts
these are at least the common pinouts used

you may find other information that may be helpful here
www.yuriystoys.com/p/msp430-launchpad-quadrature-dro.html

Thanks for the replies guys, so if I understand correctly, linuxcnc will be able to read the scales ok, now how do I tell it to use the information for position feedback so it is not relying purely on the number of steps it send the motors for correct positioning?

Is this a relatively simple thing to do or is some programming needed?

now how do I tell it to use the information for position feedback so it is not relying purely on the number of steps it send the motors for correct positioning?

If it were that simple everyone would do it.

With steppers all you will get is a system that knows with greater accuracy when you have lost steps.

Unless the commands are controlled by the actual position relative to desired position,
closed loop does not work.

I am trying to decide whether to use steppers or servo's on my mill

If you use servos, you can have a proper closed loop.

regards

their was a post on the wiki , showing how to work with steppers and encoders, although the files seem to have become lost , using steppers and only a parallel port bob ,is difficult
and quite a bit of scripting files

however using encoders with say a mesa 5i25 /7i76 for steppers or with 7i77 for servo is for the most part painless

I have not done it, but you can use steppers with encoders utilizing the Pico-Systems Universal Stepper Controller also.

Thanks Andy, that sounds like what I need, and points me in the direction of more reading- a good excuse to stay out of my unheated workshop in the depths of a Tasmanian winter. It's a bright sunny day today, but the hard frost won't be gone until after lunch, not conducive to hands-on working with metal...........