Pegasus Astro DMFC Focuser Bug/Crash

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chromus
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Joined: Wed Nov 29, 2017 11:40 pm

Pegasus Astro DMFC Focuser Bug/Crash

Post by chromus » Wed May 16, 2018 8:10 am

Hi Robin,

The Pegasus Astro DMFC focus controller uses +ve/-ve integer values, it is designed to be set to 0 at an arbitrary focus point and then can be driven in the +/- from this reference point.

The problem comes that the design of the SC focus interface only accepts +ve integers so if the value is -ve it crashes on connection.

The ASCOM driver for Pegasus allows the focuser to be sent a goto 0 command on connect, which stops it crashing on connect, but the
UI won't then allow it to drive in the -ve direction below 0.

Adding the +ve values only details to the manual would have saved a bit of head scratching.

Allowing a checkbox protected "allow -ve values" and associated functionality would help us out, this is becoming a widely used device as it's cheaper and more universal than the market incumbents.

Thanks in advance, Phil

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admin
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Re: Pegasus Astro DMFC Focuser Bug/Crash

Post by admin » Wed May 16, 2018 4:11 pm

Hi Phil,

really this one should go to Pegasus Astro to fix their ASCOM driver as they are not obeying the Ascom focuser specification which states
The focuser can step between 0 and MaxStep. If an attempt is made to move the focuser beyond these limits, it will automatically stop at the limit.
(from https://www.ascom-standards.org/Help/Pl ... axStep.htm)

ASCOM is a big minefield already because the 'specification' is not well defined in a number of areads meaning that it can be interpreted in different ways by different manufacturers.

if there was no hope of an update from Pegasus or the specification was unclear here I'd add a workaround, but I think the right thing to do is to approach them first and ask them to fix their ASCOM driver to obey the specification.

cheers,

Robin

chromus
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Joined: Wed Nov 29, 2017 11:40 pm

Re: Pegasus Astro DMFC Focuser Bug/Crash

Post by chromus » Mon May 21, 2018 2:03 am

Thanks for taking a look into this for me.

I will have to go to the method you describe, it's disappointing that they decided to go "off book" and implement something which at face value is so good, but makes interoperability so unreliable.

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Re: Pegasus Astro DMFC Focuser Bug/Crash

Post by admin » Mon May 21, 2018 1:19 pm

Do come back to me if they are unresponsive to fixing this. I will anyway try to fix the crash caused by the -ve value (as crashes are always bad).

thanks,

Robin

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