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<== Date ==> <== Thread ==>

Subject: Re: Pro-Dex OMS MAXv card reading limit-switches
From: "Martin L. Smith" <mls@aps.anl.gov>
To: junkes <junkes@fhi-berlin.mpg.de>
Cc: tech-talk@aps.anl.gov
Date: Thu, 12 May 2011 08:20:11 -0500
Sounds like you are using normally open limit switches since the limit
input on the MAXv is pulled high. This means that if there is a open
circuit (cable disconnected) on the limits then you will never see a limit
switch hit.

You would be much better off (and safer) if you used a normally closed
limit switch to ground. That way if the cable gets disconnected then you
will always be hitting the hard limit. Then your switch input will be logic
high when hit.

This does mean that you will need to tell the MAXv that a logic high is a
limit hit by using the LT command. Each of the limits on an axis may be
configured as active high (LTH).

Marty

junkes wrote:
Using OMS MAXv-card i always get only the the state of the PLUS-LS

Never the MINUS_LS even if i change the wiring (PLUS-LS <-> MINUS-LS)

The switche input is low when hit

Motor-6.5

Regards,
Heinz


MSTA R Motor Status ULONG The motor status as received from the hardware. The MSTA bits are defined as follows:

       1. DIRECTION: last raw direction; (0:Negative, 1:Positive)
       2. DONE: motion is complete.
       3. PLUS_LS: plus limit switch has been hit.
       4. HOMELS: state of the home limit switch.
       5. Unused
       6. POSITION: closed-loop position control is enabled.
       7. SLIP_STALL: Slip/Stall detected (eg. fatal following error)
       8. HOME: if at home position.
       9. PRESENT: encoder is present.
      10. PROBLEM: driver stopped polling, or hardware problem
      11. MOVING: non-zero velocity present.
      12. GAIN_SUPPORT: motor supports closed-loop position control.
      13. COMM_ERR: Controller communication error.
      14. MINUS_LS: minus limit switch has been hit.
      15. HOMED: the motor has been homed.

The record is put into MAJOR STATE alarm if either SLIP_STALL or PROBLEM bits are detected. If HLSV is set, then the record is put into HIGH alarm if either a high soft limit or hard limit (PLUS_LS) has been reached. Similary for the low limits.


References:
Pro-Dex OMS MAXv card reading limit-switches junkes

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