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

Subject: XPS Q8 issue with indexHomeSearch sequence
From: Russ Berg <[email protected]>
To: "[email protected]" <[email protected]>
Date: Tue, 1 Mar 2016 14:54:49 +0000

Hi All, a tech talk search for this issue resulted in 0 hits so I thought those of you with XPS Q8 controllers might not know.

 

Recently I nearly destroyed a $600 in vac limit switch when the stage controlled by the Newport XPS Q8 failed to respond to a + limit switch it was already sitting on and continued to move in the + direction.

I verified that the limit switch worked correctly and found that the homing procedure as it is defined in the manual (paste of relevant section below) worked as advertised but ONLY if the stage was not already sitting on the + limit switch. I hadn’t noticed this problem over the last year because in all the times I homed the stage I had never tried homing while on the + limit switch. It appears that the Q8 is waiting for the event of the limit switch being hit and does not get a current limit switch state or poll it during the homing sequence and as a result it will merrily continue moving + until a hard stop …or smoke.

 

I just received an email back from Newport acknowledging this issue and that they were able to recreate it. Tech support said that they will refer the issue to the “design team” to have it corrected.

 

The manual states the following:

  3. IndexHomeSearch is used with positioners that have a home index, but with no

hardware home switch signal. In this process, the positioner initially moves in the

positive direction to find the index. When a + limit switch is detected, the direction

of motion reverses until the index is found

 

a screenshot of the versions the Q8 is running:

 

 

~~~~~~~~~

Russ Berg                                     Software & Controls

e-mail: [email protected]   Canadian Light Source

ph: 306 657 3572                         University of Saskatchewan

fax: 306 657 3535                        Saskatoon SK S7N 0X4

 


Replies:
RE: XPS Q8 issue with indexHomeSearch sequence Mark Rivers

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