Three phase motors with directional contactors and encoder

Hello, I have a weird old surface grinding machine with very low backlash in its axes. The main hydraulic axis works fine, the Z axis is driven by a three phase motor and the Y is driven by another three phase motor.
My buttons drive the contactors to move the motors CW or CCW, but it is not enough for me, as I would like to run it fully automatically.

can I use an encoder to drive this motor? How can I choose that my axis position and direction comes out as a digital output for CW, another output for CCW, all of this while controlling its position with low tolerance?

This is probably done in Hal, are there any examples available?

ill Be using some used heidenhain encoders with very good precision, which I have interfaced with linuxcnc successfully, so no problem here. 

Sorry I wasn’t very specific.
I don’t mean to use the encoder to drive the motor. I mean to use the encoder feedback to know where the motor is.

The part that I have no idea how to do, is how I can use a mesa board to control the motors.
I have everything done electrically: closing one contractor would move CW, closing the other would move CCW. I can use mesa board outputs to drive these contactors.

I just don’t know how it would be done in Hal
Linking an output to the direction of an axis, and another output to the opposite direction.
All of this while “looking” at the encoder that I have connected to the motor for more precise control..

I don’t need high precision.

santy wrote:

I don’t need high precision.
 

Just to make sure we're all on the same page...

The Z-axis is, from the operator's position, the forward-backward axis in/out from spindle axis - right?
The Y-axis is the left-right table traverse, right?

If so, you are correct in that you don't need/want 'high' precision.  Just enough on Z to get an approximate stepover.

My suggestion would be to either use a PLC (or arduino), or use LCNC as a PLC via classic ladder.  You don't need the trajectory control part of LCNC.  Just some adjustable limit switches for both axes, plus an encoder knob and a pushbutton or two to start/stop left-right and start/stop incremental stepovers.

The end result will be fairly 'dumb', but you can have an adjustable left-right stroke length as well as an adjustable stepover increment (plus auto-reverse) for Y axis.  The auto-reverse won't be super-useful as you aren't (or haven't mentioned) how to control X-axis downfeed.

If this sounds like a useful arrangement we can help work out the details in ladder and hal.

Hello, thank you again for your help in this post on my previous post on the 611 drives!! This is a good idea.

I have a damage 7i96s board with working IO and encoder (only stepgen4 works, the others dont) and I’ll use it in this machine hahah.

The left and right stroke is imposed manually in a very clever way, I could send you a video via Discord or something.

The grinding head goes down and up in an extremely precise lead screw so I can get very good precise movement even with this dumb motor.

The Y axis (moving the grinder forward and backward) is the one I want to “CNC” the most, so that I don’t need to be using the machine constantly.

I’m not confident with Arduino, much more with linuxcnc

Sounds like you want to automate all three axes.

Some pics of the machine would be helpful, along with a wiring diagram.

And a better description of the mechanism the moves the head up and down.  It may make sense to fit a stepper motor to drive the head up and down and use your one remaining stepgen to manage that action, with the other axes driven via contactors and adjusted with timer values stored in ladder or somewhere else in LCNC.