Re: Homing problem in Mar 15 build

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Tim Goldstein wrote:

> I just tried actually homing with the Mar 15 build on RedHat 5.2 and I am
> having a problem. once I contact the home switch the axis is continuing to
> travel about .1 " then it reverses direction and backs up a few thousands
> then it starts back in the original direction of the homing at a rate of a
> few steps per second and keeps going for 5 or so seconds.
>
> This is unlike homing has been working. Previously the direction would
> reverse as soon as the homing switch was contacted and then it would come at
> the switch again very slowly and stop the instant the contact closed. No
> extra movement past the switch closing at all.
>
> Anyone else try to home under freqmod with this build? I have not tried it
> with steppermod.

The old homing procedure was to locate the switch, period.

I believe the new procedure (should only be used with encoders with a
Z (index) channel), is to use the switch to get close to one specific
pulse from the Z channel, and then locate the first Z pulse after the
switch closes.  If you do this right, it is possible to set up a home
position that will precisely locate from either direction, and be accurate
down to 1 or 2 encoder counts.

Jon