The Mesa 7i76 spindle I/O only operates as enable and dir as far as I know. The 
notes say the enable output is hard linked with the enable for the analog 
output. It all seems to work properly (outside if the instant reverse issue) 
when testing in PnCConf's open loop test. Nothing in LinuxCNC which leads me to 
believe there is a config issue somewhere in the HAL/INI.

Setting the signs of the search and latch velocities just causes the axis to 
locate the home switch in the correct direction, incorrectly set that as zero 
and then search for the positive home location in vain as it runs into 
overtravel. How do I tell it that the home switch location is not zero, it is 
actually 18 or whatever?

I'll look at the toolchange reference, thanks.


------Original Mail------
From: "andy pugh" <bodge...@gmail.com>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Sent: Wed, 17 Sep 2014 15:20:30 +0100
Subject: Re: [Emc-users] New to LinuxCNC and PnCConf and need some help...

On 17 September 2014 13:59,  <p...@wpnet.us> wrote:

> 1. The biggest issue currently - After some fiddling I have the Hitachi VFD 
> controlled spindle operating in the PnCConf open loop test where I am able to 
> run it forward and reverse at various speeds. I have the spindle encoder 
> connected (A and Index only, not sure on CPR currently) and in HALscope I can 
> see the A pulses and index pulse. I haven't been able to get the spindle to 
> operate in LinuxCNC however no matter what I've tried. Another issue I have 
> found is that when running in reverse and stopping, LinuxCNC drops the 
> direction line before the VFD has completed the decel ramp, causing the VFD 
> to slam the lathe into forward for the duration of the decel, obviously not a 
> desirable thing.

I can see why that would happen, but that isn't what I see with my
lathe/vfd so I suspect that it is something to do with the config at
the VFD end.
I think it is best to configure the VFD for "two button" operation
with one terminal for FWD and one for REV. Then when the spindle-fwd
or spindle-rev signals go false then the VFD simply switches off and
ramps down at its internally programmed speed.
It sounds to me like you may have the VFD wired for ON/DIR rather then FWD/REV.

I am having trouble reconciling the statement that you can't get the
spindle to work with LinuxCNC with the statement that something funny
happens when LinuxCNC drops the dir line.

> 2. I've got the axis homing working in the direction it seems to want to run, 
> i.e. in the negative direction, however this seems like a bad idea on a lathe 
> to me. If I have a part in the spindle and need to re-home for some reason, 
> something not unexpected on a stepper machine, homing in the negative 
> direction will crash the toolpost into my part. It would seem better to home 
> in the positive direction and "zero" to the max travel of the axis. I haven't 
> figured out how to do this.

This is a matter of setting the signs of the search and latch
velocities in the INI. My lathe homes in the positive X and negative Z
direction (as homing into the tailstock sounded like a bad plan).

> 3. The lathe has an 8 position unidirectional stepper driven tool turret with 
> a home switch. I currently have the stepper drive wired to stepgen 2 (0=Z, 
> 1=X). I was able to configure an A axis so I can manually move the torret, 
> but I've not found any docs so far that give me much of a starting point to 
> figure out how to configure the tool turret properly for automatic changes.

There are HAL components to control that style of changer here:
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ContributedComponents#Boxford_Lathe_ATC_toolchanger_component

They may need tweaking for your particular application, but help will
be available with that.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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