How to prevent pier crash: Ap1100 with AE #APCC #Absolute_Encoders


Shailesh Trivedi
 

Hi,

I am a new owner of an AP1100 which has user-installed absolute encoders. I just polar-aligned my scope on a new pier and now need to set up limits. How do I prevent the camera end from crashing into the pier (slewing to images or accidentally)? Is there a way to manually slew close to a crash and set a limit such that it will not crash? Or is there a better way? Since crashes could occur at certain DEC.

Shailesh


Roland Christen
 

Our guys at AP can help you set up your mount. Give them a call.

Roland

-----Original Message-----
From: Shailesh Trivedi <strivedi@...>
To: main@ap-gto.groups.io
Sent: Thu, Sep 2, 2021 1:23 pm
Subject: [ap-gto] How to prevent pier crash: Ap1100 with AE #APCC #Absolute_Encoders #APCC

Hi,

I am a new owner of an AP1100 which has user-installed absolute encoders. I just polar-aligned my scope on a new pier and now need to set up limits. How do I prevent the camera end from crashing into the pier (slewing to images or accidentally)? Is there a way to manually slew close to a crash and set a limit such that it will not crash? Or is there a better way? Since crashes could occur at certain DEC.

Shailesh

--
Roland Christen
Astro-Physics


Worsel
 

Shailesh

Complex topic!  I assume you refer to Meridian Limits.

I would suggest reading Section 6.16 (Meridian Limits) in the APCC documentation.  It's the same section whether you have APCC Std or Pro version.  Ray's cautionary words are in the first paragraph.

"However, like any powerful feature, you MUST understand how the meridian limits work. It is vital that you understand what they
CANNOT do as well as understanding what they can do!"

The section on Horizon Limits is useful as well.  Section 6.15

Bryan


ap@CaptivePhotons.com
 

I hope @Shailesh or someone will post a summary afterwards, as I am wondering this as well.  From what I read the meridian limits control tracking crashes, but do not prevent slew crashes.  The Safe Slew (which I think is automatic) avoid CW slews between point A and B, but doesn’t prevent a human from requesting a slew into point B which might cause a crash.

 

Do I misunderstand?   Is there a way to also prevent a stupid-human-trick that might slew into the mount?  

 

Humans are dangerous, but persistent.  😊

 

Linwood

 


Worsel
 

Linwood

A good explanation from the Troubleshooting section, but perhaps not answering your question is

"APCC has a sophisticated meridian limits mechanism that will allow you to define the limit the mount can track past the meridian at multiple declination values. Will this also prevent slews to these positions? I will often be starting imaging east of meridian but would like reasurance that GOTOs with a negative meridian delay won't hit anything. 

APCC (and also the ASCOM driver) have "safe slews" built into them to prevent slews that cause collisions in "counterweight-up" conditions. The slews occur in multiple stages. If you are starting a
slew from a counterweight up position (i.e. you have tracked past the meridian), the first part of the slew will be in right ascension only. The mount will move in RA until the mount enters a normal, counterweight down orientation. It will then slew in both axes until the RA reaches the meridian, and the Dec fully completes its slew. Finally, with the Dec having arrived at its safe position, it will then complete the slew in RA only to the starting point east of the meridian with the counterweight up."


Bryan


ap@CaptivePhotons.com
 

Worsel wrote:

  • A good explanation from the Troubleshooting section, but perhaps not answering your question is…

 

I had read that which is why I mentioned tracking vs slewing, as well as the safe slew.

 

I am still working on refining my imaging train, and I have hopes that as long as I do not go counterweight up I cannot crash, but I am not yet sure.  I know on prior mounts I had to stop about 30 minutes early and wait about 30 minutes past meridian for some DEC angles.

 

So it may be moot once I get everything set up.


But my reading so far has led me to believe the limits apply only to tracking, and while it tries to prevent … let’s call it incidental crashes with the safe slewing (which is great), I think it means a human can still slew into coordinates that collide even if you have meridian limits set.

 

So I mostly want to confirm if I have that right, or if there is a way to carve out a “do not go there ever” space, how you do it?

 

Linwood

 


Shailesh Trivedi
 

Thanks Roland. I spoke with George and he was kind enough to walk me through it. I am all set. 

Shailesh


Shailesh Trivedi
 

Hi Bryan,

Thanks I read it and re-read it, got a bit lost, until I spoke with George.

Shailesh