sorry gene i didnt see i sent this private
-------- Forwarded Message --------
Subject: Re: [Emc-users] trying to connect a encoder from cnc spindle
motor to schiender vfd
Date: Wed, 12 Feb 2020 17:55:34 +0700
From: Thomas J Powderly <tjt...@gmail.com>
To: Gene Heskett <ghesk...@shentel.net>
hello
On 2/12/20 4:52 PM, Gene Heskett wrote:
On Wednesday 12 February 2020 01:49:34 andrew beck wrote:
the option I just thought of while googling is, can I convert the sin
cos format in to a normal TTL or something like that? even 1000 ppr
would be heaps it is only on the spindle.
One thing you might try, is to use a couple of those $2 rs485 to ttl
boards. I bought an encoder to put on the rear of the spindle motor,
only to find on its arrival it had a balanced output of only a few
millivolts, nothing ttl about it. So I made a small hammond box with
two of those in it to translate it to ttl for feeding the encoder in
the 5i25. Works a treat. But because the sin/cos is generally
magneticly generated, its signal may get weak enough to miss count at
very low speeds, which might lead to enough error to make sloppy
threads when rigid tapping with a peck routine. It might miscount at
the turnaround at the bottom of the hole.
I just want to get the data into the vfd so It knows when the motors
is slowing down. and so I can rigid tap and the existing encoder is a
high quality heidenhian one so might be good to keep it if it is not
too much trouble.
ISTR Jon has a board for that, see at PicoSystems.com.
I used heidenhain scales and encoders exclusively , but on heidhenain tnc.
heres something relevant
from
https://www.practicalmachinist.com/vb/deckel-maho-aciera-abene-mills/deckel-nc-upgrade-cons-pros-299846-print/index11.html
"""
Here is what I will be using to interface my existing scales to LinuxCNC
via MESA hardware:
IC Haus TW28 Interpolator
"""
thats is talking about an interface chip designed to read the sin cos
output of the heidenhain encoder.
I do not think it is what's needed for the newer 'endat' encoders.
I have seen simpler encoder interfaces but they simply made a single
count per transition
where thes ichaus chips interpolate same as the heidenhain nc's did,
giving you many counts per transition
https://www.ichaus.de/keyword/Interpolators
( the newer scales and encoder maybe endat and may use biss ( past my
field op years ,
AndyPugh and Jon may have some threads on the subject
so make sure you know the full heidenhain part number when hunting info
that means the full identifier is more than just 1 box on the label )
regards Andrew On Wed, Feb 12, 2020 at 7:43 PM andrew beck
<andrewbeck0...@gmail.com> wrote:
Hi guys wondering if anyone has any ideas here. I have a heidanhain
spindle motor that runs up to 10000 rpm and has a 5v sin cos encoder
on it. I am currently controlling the motor with a schiender vfd. I
am talking to the support engineers here in New Zealand about buying
a encoder card so I can get better low down torque. If I run the
card in full encoder closed loop control in the vfd I can get 200
percent of the torque right down to 0 rpm for 30 seconds or so which
is pretty useful. I am currently just running the drive in Variable
frequency control which rapidly looses torque at low rpm. Anyway
they have a bunch of cards I can use but don't have a encoder card
that is suitable for sin cos encoders. I have no trouble changing
the encoder but am not sure if I can get a source of encoders that
spin up to 10k rpm. Anyone have any suggestions? regards Andrew
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Cheers, Gene Heskett
hth
tomp
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