Intermittent error PHD2 is Unable to make sufficient corrections to Dec axis

[Ryan Heuer]

Hi all,

So this has been an ongoing problem for me this whole year. Periodically, PHD would "lose connection" to my mounts DEC axis (the RA works fine). It sends corrections but the mount doesn't respond.  Sometimes it happens when I first start guiding at the beginning of the night, sometimes it happens after a meridian flip. Only way I have found to remove the issue, is to completely reinstall PHD. Ive tried resetting all configurations, Ive tried recalibrating (which fails because the mount DEC axis doesn't respond). Im beginning to think its a COMM issue, but at the same time I don't get how reinstalling PHD can mitigate this problem (temporarily). Any help would be great. Ive included logs below.

Mount : SkyWatcher EQ6-R Pro

Guidecam:  ZWO ASI 290mm

Log file: https://openphdguiding.org/logs/dl/PHD2_logs_X8gH.zip

[bw_m...@earthlink.net]

I think this is pretty straightforward and I’m afraid you’ve wasted a lot of time with all this un-installing and re-installing.  Have you looked at any of the logs with PHDLogViewer?

 

https://openphdguiding.org/phd2-log-viewer/

 

Based on what I can see, your worst problem starts when you do a meridian flip or when you’re trying to start with a calibration that was done on the opposite side of the pier from where you’re pointing.  That triggers an alert message at the top of the screen that says:

 

02:51:12.995 00.000 2984 Alert: PHD2 is not able to make sufficient corrections in Dec.  If you have just done a meridian flip, check to see if the 'Reverse Dec output option' on the Advanced Dialog guiding tab is wrong.  Otherwise, check for cable snags, try re-doing your calibration, and check for problems with the mount mechanics.

 

Well, that’s probably why you get runaway-Dec-guiding – I think the “GSServer” mount driver requires this option to be set and it isn’t.  Here’s the description from the manual:

 

https://openphdguiding.org/man-dev/Advanced_settings.htm#Reverse_Dec_output_after_meridian_flip

Or you can use the built-in wizard tool to confirm what is needed for this setting:

https://openphdguiding.org/man-dev/Tools.htm#pierflip_cal_tool

 

The reason all the uninstalling seemed to help is that it forced a new calibration to be done.  That’s all.  And of course you can force a calibration whenever you want by just doing shift-click on the guiding icon.  Since you’re having so much trouble, you should make it a practice to do a fresh calibration at the start of every night’s session - but you can’t do that when pointing at the celestial pole.  You should be pointing near Dec=0 and reasonably close to the celestial meridian.  Since your mount probably has substantial Dec backlash, you can clear it manually with these steps:

Start looping guide camera exposures on a field with usable stars, preferably near Dec=0 and within 15 degrees of the celestial meridian
Using the hand-controller, move the mount north ('up' arrow) until you see the stars in the display moving
Start the calibration

This will have to be done *every time* you do a fresh calibration.

 

I think it would be a very good idea to re-read the manual carefully, including the Basic Use and Trouble-shooting sections.  Then review the best practices guide to help cut down on basic operational mistakes:

https://openphdguiding.org/phd2-best-practices/

 

Once you have a better understanding of what PHD2 is doing, you can measure the performance of your mount and start to see where it has shortcomings and then how best to mitigate them:

https://www.dropbox.com/s/os1thorvswmzaul/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0  

 

Good luck,

Bruce

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/b3b231c3-6018-472c-b357-f2c491431be5n%40googlegroups.com.