Alert message: Pulse guide command to mount has failed

[Dirk de Gans]

I have bought a new ZWO AM5 mount, and I am completely new to the world of guiding and Ascom, since I come from an EQ5 with RA-motor. First night out I kept getting these messages "Pulse guide command to mount has failed - guiding is likely to be ineffective", which seems to indicate a timing issue in the mount driver. I was not sure which driver to choose in PHD2, because both "ASI Mount (Ascom)" and "Device Hub Telescope (Ascom)" seemed to work. The laptop is fairly new (AMD 5600u 6-core with 16GB memory), so I don't expect it to be the problem. Polar aligning and platesolving worked excellent. I was guiding with my ASI 224MC Pro and the ZWO mini guidescope (30mm, 120mm f.l.). My logfile can be found at: https://openphdguiding.org/logs/dl/PHD2_logs_w9Rs.zip.

[bw_m...@earthlink.net]

It looks like there are several problems here.  But if you want to focus on the pulse-guide command timeout, you should eliminate the ASCOM Device Hub.  That’s just an extra layer of software in the communications pipeline to the mount and it shouldn’t be needed for your mount.  The Device Hub is really intended for situations where the mount driver isn’t capable of handling more than one attached application at a time.  If that isn’t a problem, eliminate the Hub.  The PHD2 alert means the mount driver has never reported completion of a previous command to pulse-guide it.

 

The other major problems include all the camera timeouts you got in the first hour of operation.  Did you do something explicitly to fix that?  It indicates potential problems in the USB subsystem which can also affect communications with the mount.  Another problem is the events that look like this:

 

 

All these huge peaks represent very large apparent excursions of the guide star.  The most likely source of these problems is the flimsy finder-scope assembly you’re using for guiding.  You’re in the unfortunate situation where a mechanical shift of the guide camera by only 3-4 microns (less than 1/10 the thickness of a human hair) results in a guide star excursion of over 6 arc-sec.

 

I think the first priority should be to resolve any and all USB communication problems in addition to removing the Device Hub and seeing if the pulse-guide timeouts go away.  There is an extensive section in the PHD2 manual regarding USB-related problems:

 

https://openphdguiding.org/man-dev/Trouble_shooting.htm#Problems-_Camera_Timeouts

 

Good luck,

Bruce

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[Dirk de Gans]

Thank you for the speedy response. As soon as we have a clear night I will try again without the Device Hub and with power saving shutdown of USB-ports disabled. The other problems you noticed were probably due to my experimenting with the Sharpcap focussing aid. I frequently touched the guidescope and (re)connected the camera. Testing today in daylight (as suggested in the troubleshooting section) showed no connection losses at all.

Op woensdag 14 december 2022 om 03:21:23 UTC+1 schreef bw_m...@earthlink.net: