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On my lathe, I have mechanical limit switches on X+ and Z+. Rear mounted tool post
I just installed DMM Servos, which output a reference signal for homing.

On my knee mill with All in One DC, when it homes:
Each axis homes to a mechanical limit switch, then backs off of them and the control hunts for the encoder index pulse and calls that home.

I want to accomplish the same type of homing sequence except that my index pulse will come in on an input.
Input 1=Z axis Limit Switch
Input 2=X axis Limit Switch
Input 3=Z axis index pulse
Input 4=X axis Index pulse

What is the best way to accomplish this? (I am using Acorn with CNC12 to drive the DMM DYN2 AC Servo drives)
Is this a PLC change? or can it be done with a Macro?

I posted here because I figured maybe Marc or Scott if they had the time might catch the question here.

Thanks in advance,
Marty

This is an interesting question. I am now wondering how it handles a C axis home.

frijoli wrote: ↑Sat Dec 16, 2017 1:37 pm This is an interesting question. I am now wondering how it handles a C axis home.

Are you going to home the C axis?
You might need a sensor on the spindle for that....

martyscncgarage wrote: ↑Sat Dec 16, 2017 3:24 pm

frijoli wrote: ↑Sat Dec 16, 2017 1:37 pm This is an interesting question. I am now wondering how it handles a C axis home.

Are you going to home the C axis?
You might need a sensor on the spindle for that....

I would think I would home it. I was going to use the encoder z output.

frijoli wrote: ↑Sat Dec 16, 2017 4:37 pm

martyscncgarage wrote: ↑Sat Dec 16, 2017 3:24 pm

frijoli wrote: ↑Sat Dec 16, 2017 1:37 pm This is an interesting question. I am now wondering how it handles a C axis home.

Are you going to home the C axis?
You might need a sensor on the spindle for that....

I would think I would home it. I was going to use the encoder z output.

I think you can do that. It will revolve until it finds the index pulse. Just set the input on Acorn to home switch.

Marty,

Your index pulse must come in on an encoder input in order to do "normal" homing. I suppose you could modify your home file to do an M105 or M106 which are move minus and move plus to switch but I'm not sure why you would want to do that. Is the index pulse not include in the encoder signal itself? ie.. A, A-, B, B- and Z, Z- or I, I- or "Marker"

diycncscott wrote: ↑Mon Dec 18, 2017 9:41 am Marty,

Your index pulse must come in on an encoder input in order to do "normal" homing. I suppose you could modify your home file to do an M105 or M106 which are move minus and move plus to switch but I'm not sure why you would want to do that. Is the index pulse not include in the encoder signal itself? ie.. A, A-, B, B- and Z, Z- or I, I- or "Marker"

Hi Scott,
Because this is for Acorn, there is no way for Acorn to see the index pulse. Yet the DMM Technologies DYN2 and DYN4 provide a Zero Reference signal output for the purpose of homing a machine. So my hopes were to mimick what CNC11 does, hit the limit switch back off, hunt for the index pulse, but since it does not come in via the encoder cable, it would have to come in via an input.

Thanks Scott, I appreciate the response. There are a couple other Acorn users wondering if this could be done as well. I know you are a very busy guy so your time and input is appreciated.

Marty

I'm sorry, I saw ALLIN1DC at the top and missed the Acorn part at the bottom. Move to "switch" might be your best bet then, just watch your feedrates while hunting for the marker.

diycncscott wrote: ↑Mon Dec 18, 2017 1:40 pm I'm sorry, I saw ALLIN1DC at the top and missed the Acorn part at the bottom. Move to "switch" might be your best bet then, just watch your feedrates while hunting for the marker.

Thanks Scott.
I'm trying to figure out if a change to the PLC is needed or a custom homing macro to automate this homing routine, and how that might look.

No custom PLC needed, M105 and M106 look for the state of an input number, no PLC logic needed. You could set them to unused in the Wizard if you like.

M92 /Z L1 ;Move to Z+ home switch, back off until it clears.
M105 /Z P-4 F3 ;Move Z minus at 3ipm until input 4 closes
M26 /Z ;Set Z home here

M91 /X L1 ;Move to X- home switch, back off until it clears.
M106 /X P-3 F3 ;Move X plus at 3ipm until input 3 closes
M26 /X ;Set X home here

....lather, rinse, repeat

You may need to play around with the rates to get it to stop on the pulse. You can change the moves between looking for switch to open or close by changing the sign of the input # ie.. change -3 to 3