Re: problem with GTOCP4

Christopher Erickson

I have been suspecting that there is a subtle bug in the CP4 code for logical horizon limits for some time now. Sometimes my Mach1 with CP4 will not go East/West beyond some point near the meridian and it takes several unparks from known positions before it gets reset and everything goes back to normal. For me, it seems to mostly show up when using the hand controller. I have never been able to really narrow down the behavior or reproduce it on command. All I know is that it might take several restarts from a known park position to clear it.

Switching to a CP3 just makes sure that I will lose my PEM training in the CP4. And the CP3 too, of course.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Tue, Aug 4, 2020, 1:43 AM Steve Reilly <sreilly24590@...> wrote:

I had a similar incident with my AP1200 w/CP4 and switched back to the CP3. Howard found that the coordinates in the CP4 were preventing the mount from moving east. I could use the N/S/W buttons to move the mount but not the east. How those coordinates became errant is beyond me. I was running ACP Expert when this occurred as usual and it had been a successful night of imaging. It happened when it was running the shutdown script and trying to park the mount before closing the roof. I was also using APCC Pro at the time as usual. NO clue as to how this happened Howard cleared it up ad has been running (sort of) since. With the bad weather it’s been more not running then running since. What I had not tried was manually moving it to say Park 4, kill power, and then reconnect with then doing a resume from Park 4. Maybe give that a try just in case. Won’t be dead on but maybe get you back in service and then recalibrate on a star or do an image link/plate solve to refine your position.





From: <> On Behalf Of Geert
Sent: Tuesday, August 4, 2020 3:43 AM
Subject: [ap-gto] problem with GTOCP4




Since March 2020 I’m using a GTOCP4 on my AP1200 without issues.  Last night however, after some hours of imaging, when I issued a GoTo from TheSky to another object, the mount did not respond anymore (using APCC Standard on PC). 


A Park 4 command only gave a “slewing” window but the mount did not move. 


I got a motor stall error (only once), cleared it from the log and this did not come back after further attempts.  Mount is well balanced. 


LED was amber.  I checked the power cord and tried another power source, LED remained amber.


Disconnected/reconnected power lead from CP4, LED was red first but then amber almost immediately.


Disconnected from APCC, connected my handcontroller: LED remained amber, but I could move the mount E-W but in DEC only one direction (S) worked. Connected DEC lead to RA motor, same result – only one direction worked.  Park commands did not work, GoTo’s did not work.


I then changed the CP4 with the CP3 from my Mach1 mount and no more problems, all directions work, park commands work, GoTo’s work, LED is red all the time.


Any idea’s, someone?






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