Experimental Physics and
Industrial Control System

Torsten Bögershausen via Tech-talk <tech-talk at aps.anl.gov> · Fri, 24 Mar 2023 05:59:39 +0100

Hej LiangChih Chiang,
there is no good solution to handle this in software, as far as I know.
The best thing would be to talk out the encoder (mechanically),
rotate it by hand so that the value of the encoder at the negative
limit switch is close to zero, with  a little margin.
Say 1000 or so, as an example.
Put the encodet back into the mechanics, and verify that there is no 
Overflow / wrap around through the whole driving range from 
Low- to the high limit switch.

> On 24 Mar 2023, at 04:32, Chiang, Liang-Chih [江良志] via Tech-talk <tech-talk at aps.anl.gov> wrote:
> 
> Hello,
> 
> I use Galil DMC-4080 controller to read Renishaw absolute encoders(26 bits).
> So far so good.
> 
> However, I conjectured that I encounter the situation where encoder's value
> exceeds its maximum(2^26 = 67,108,864).
> 
> 66,000,166 is the encoder value initially.
> 59,829,149 when going to negative limit switch, which is ok.
> 899,833 when going to positive limit switch, which is abnormal.
> 
> What could I do to handle this situation?
> 1.  Replace the encoder scale.
> 2.  Can I remedy it in EPICS? How? I have no idea.
> 
> 
> Best regards.
> 
> 
> LiangChih Chiang
> NSRRC
> Beamline Group
> email：chiang.lc at nsrrc.org.tw 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System