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Celestron Nexstar GPS 11 not working. Trying to substitute for NexRemote. Unable to connect...

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#1 pelfra

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Posted 03 August 2020 - 07:23 AM

Hello passionate observers,

 

I got my hands on a Celestron Nexstar 11 GPS last spring. With the help of a few people from this forum, I have managed to clean the optics to near-perfection and collimate the instrument very well. Then came the time to have fun with it. Up to now, I have been using it without any automation. The Hand Controller, or something else, is really not in good shape. The display is somewhat loose and the cable connection to the back of the handle is quite loose, the rubber O ring is gone. Nevertheless, it lights up, most of the time, and displays the initial setup message. The automatic leveling starts and stops with the tube on a 2o deg vertical inclination. I go to the Level Calibration routine, saved it, restarted and leveling went wrong again. Then the display becomes corrupt and everything freezes. Automatic North alignment also fails after a complete turn. Motor Control seems to be following speed settings and pointing. But after 15 minuted of use, it too fails, Hand Controller display become garbled and everything freezes. In other terms, the Hand Control seems to be more or less « kaput ».

 

OK then, why not substitute for the NexRemote software? I downloaded it and tested it and it seems to be stable. Since I don’t thrust the scope Hand Controller I prefer to connect directly to the PC Interface Port Fork 8 conductor RS-232. I connect the cable to PC Serial Port DB9M.

 

This diagram :
https://www.nexstars...arCablingV5.pdf

 

I follow the [A] path on top.

 

I bought this cable. It should to the job :
https://www.infinite...-500-06-inf.jpg

 

But up to now, no success at getting the software talking to the scope. I tried all connection settings. I do have a few interrogations.

 

The Nexstar Hand Controller may be disconnected if I connect NexRemote directly to the Fork Port. If it’s defective, it SHOULD be disconnected, right? After all NexRemote, along with NexGPS, are supposed to replace it completely. So I disconnected the Hand Controller and got no improvement.

 

Could it be the that the cable I got does not connect correctly to the computer? I could have to swap individual wires to obtain the right connection. I only found the wiring diagram for the DB9 five pins connector of the Hand Controller. I could easily modify the RJ45 connection if I got my hands on the right diagram.  Any hint?

 

I like manual operation of the instrument, but I’m missing A LOT without computer control.

Thanks for your help!

Francois Pelletier

https://photos.app.g...LLsNN27CM5s3ba8



#2 whizbang

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Posted 03 August 2020 - 07:46 AM

pelfra,

 

From your photograph, it appears you have an older Hand Control with the RS232 jack in the bottom, not a newer hand control with a USB jack?

 

You bought the wrong cable.

 

You need a USB to Serial converter.  I recommend a converter like the StarTech.com #ICUSB2321F which uses a FTDI chip instead of a Prolific chip:

 

https://www.startech...able~ICUSB2321F

 

You also need the RS232 Cable from Celestron.  Celestron Part #93920

 

https://www.celestro...ar-rs-232-cable

 

The USB to serial adapter plugs into you computer USB port.  The Celestron cable plugs into the adapter AND the bottom of the Hand Control.

 

*******************************************************************************************

 

From your description, I think your scope might be broken.  You scope should operate perfectly on the hand control.  A lot of people run into problems once they use WiFi, tablets, or PC's.  But the Hand Control should work reliably with NO problems.

 

With your freezes and lock ups and failures, are you getting any error codes on the Hand Control?  Error 17?  Error 16?

 

I suspect there is a serious problem with your mount, possibly the motor control board.  If it doesn't run on the hand control, using PC software isn't going to help.


Edited by whizbang, 03 August 2020 - 07:49 AM.


#3 mclewis1

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Posted 03 August 2020 - 09:30 AM

wizzbang, he's not connecting through the hand controller so those suggestions don't apply (well at least none of the serial connectivity stuff ... the USB-serial adapter would be helpful however).

 

Pelfra keeps showing us a picture of a cable via the link but no information about it. The PC Port on the NS GPS mounts requires a very specific and unique serial RS232 cable with a DB9 to RJ45 adapter. There are or have been 3rd party cables available to meet this requirement ... I'm just not certain that the cable Pelfra has linked to and purchased meets those requirements.



#4 Jim Davis

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Posted 03 August 2020 - 10:01 AM

You would need to make sure your cable is wired like this: https://nexstarsite....ammingCable.htm



#5 Michael_Swanson

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Posted 03 August 2020 - 08:40 PM

Hi Francois,

 

Jim's link is the correct cable for the PC Port cable.  That blue cable you found is definitely not wired correctly.  

 

Regarding the level calibration, this just stores a value in the hand control to compensate for the difference between the position of the level switch (you can hear it click when you move the tube up/down with the clutch released) and the actual "level" position.  In other words, during the GPS Align routine, it will always start at that same "somewhat" level position even after calibration.

 

Have you tried opening the back of the hand control, working out a way to secure the cable in the opening on the back, and reseating all the cable connectors (the coiled cable and the LCD panel ribbon cable) at the circuit board?  This may stabilize things.  Also, what HC and MC version numbers are displayed in the hand control menu?

 

Yes, if the HC continues to misbehave, you should disconnect it entirely when attempting to use NexRemote via the PC Port.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com



#6 pelfra

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Posted 09 August 2020 - 12:48 PM

Hi Francois,

 

Jim's link is the correct cable for the PC Port cable.  That blue cable you found is definitely not wired correctly.  

 

Regarding the level calibration, this just stores a value in the hand control to compensate for the difference between the position of the level switch (you can hear it click when you move the tube up/down with the clutch released) and the actual "level" position.  In other words, during the GPS Align routine, it will always start at that same "somewhat" level position even after calibration.

 

Have you tried opening the back of the hand control, working out a way to secure the cable in the opening on the back, and reseating all the cable connectors (the coiled cable and the LCD panel ribbon cable) at the circuit board?  This may stabilize things.  Also, what HC and MC version numbers are displayed in the hand control menu?

 

Yes, if the HC continues to misbehave, you should disconnect it entirely when attempting to use NexRemote via the PC Port.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com

 

 

You would need to make sure your cable is wired like this: https://nexstarsite....ammingCable.htm

This is exactly what I was looking for. I cut the cable and I'm rearranging individual wires to match the schematic and then clamp a new RJ45 connector.



#7 pelfra

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Posted 09 August 2020 - 02:06 PM

Hi Francois,

 

Jim's link is the correct cable for the PC Port cable.  That blue cable you found is definitely not wired correctly.  

 

Regarding the level calibration, this just stores a value in the hand control to compensate for the difference between the position of the level switch (you can hear it click when you move the tube up/down with the clutch released) and the actual "level" position.  In other words, during the GPS Align routine, it will always start at that same "somewhat" level position even after calibration.

 

Have you tried opening the back of the hand control, working out a way to secure the cable in the opening on the back, and reseating all the cable connectors (the coiled cable and the LCD panel ribbon cable) at the circuit board?  This may stabilize things.  Also, what HC and MC version numbers are displayed in the hand control menu?

 

Yes, if the HC continues to misbehave, you should disconnect it entirely when attempting to use NexRemote via the PC Port.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com

Hello Michael,

 

" it will always start at that same "somewhat" level position even after calibration"... I suppose that the next steps, like the two stars alignment procedure, would fix this behavior. If not, this scope would never be able to "go-to" anything, no? In my situation, that "somewhat" is more than 15 degrees tilt! As far as the HC and MC version numbers, I can't provide those. The display is mostly inoperative or garbled. The best I can do is to post a picture of the chips.

Link : https://photos.app.g...gt6xXq4Q2TFcPX7

 

I will try the NextRemote solution. I'm rerouting the individual wires of my cable according tho the schematic.

 

Thanks for the help.



#8 mclewis1

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Posted 09 August 2020 - 07:08 PM

Francois, That starting point is what allows the mount to have a rough idea about it's orientation and so to help it point to the initial alignment stars but it's not used for the accuracy of the goto. That accuracy is dependant on how well you actually do the intitial alignments (how well you center the alignment stars). 



#9 Michael_Swanson

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Posted 11 August 2020 - 12:04 AM

What Mark said :-)



#10 pelfra

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Posted 07 September 2020 - 12:39 PM

I'm about to give up.

 

I've built and double checked my rs232 cable and it's perfect. Pin to pin connections are 100% (diagram : https://nexstarsite....ammingCable.htm). I connected  my Windows10 PC, started NexRemote 1.7.24 and turned on my C11. Everything seems to hold well.  Then I tried the settings that should work with my scope : Nexstar GPS, GPS version 1.6, Com1, Virtual port 4 . No success. Always the same message from NexRemote : "Unable to communicate with telescope". I also tried other C11 scope and software versions, port channel and virtual port channels. Nothing, just cold deep space vacuum...

 

I lifted the cover of the motors and interface compartment of the fork base to check the quality of the PC interface connector. It looked very clean, no trace of dust or rust. By the way, the hole compartment was extra clean, sparkling.

 

What's next? The truth about this issue is that I can't even be sure that each aspect of the chain is working correctly: NexRemote looks like it operates well or does it? Does NexRemote 1.7.24 really works with Windows 10 or does it pretend to. Is my PC serial port ok? Is there someone home in my C11 base?. I can only say that despite the erratic behavior of my Hand Control, It was sending instruction to the C11 fork and the fork hardware responded correctly... until the Hand Control went crazy, each time.

 

Any suggestion? Install Windows XP SP3 and a compatible NexRemote program, just to check if the 32 bits version works?

 

I don't like to give up.     Francois



#11 mclewis1

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Posted 07 September 2020 - 10:27 PM

Francois,

 

NexRemote 1.7.23 and 1.7.24 have worked well for me for the past 3 years on a 64 bit Win10 system (the last major update was 1903). This PC is an i3 based laptop that I use to test software. Since NexRemote is the hand controller I regularly run a variety of mount control apps against that virtual hand controller before I put the software on my observatory PC. This configuration does also occasionally get connected to a real mount (an ASGT). This connection is PC > USB-serial adapter > Celestron HC serial cable > hand controller.

 

I use old (12 year old) IOGear USB-serial adapters that use Prolific chipsets. I also regularly run NexRemote on a Win7 based PC in my observatory to control a CGE mount. This connection is either the same as mentioned above or PC > (real RS232 serial port) > Celestron PC Port cable (adapter + Ethernet patch cable) > PC port on the CGE mount.


Edited by mclewis1, 08 September 2020 - 03:29 PM.


#12 Michael_Swanson

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Posted 07 September 2020 - 11:43 PM

Hard to tell where things are going wrong Francois.  It could be the PC Port is simply dead on your N11 (it died on mine about 10 years ago).  Can MCupdate see the motor control when connected via that port?  (https://www.nexstars...pgradeHowTo.htm for operation of MCupdate)  I would NOT recommend attempting to update the MC - just see if MCupdate can report the current versions of the firmware on the MC.

 

Time to locate a version 4 hand control for your mount.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com



#13 mclewis1

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Posted 08 September 2020 - 03:26 PM

I was just going to suggest that Mike ... lol.gif

 

Oh and I edited my earlier post to include the physical connectivity I'm using.



#14 pelfra

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Posted 09 September 2020 - 03:25 PM

Good news at last!

 

Mike Swanson suggested to check my Motor Control firmware with MCupdate Celestron Software. So I downloaded it and run it. I checked Port 1 first and I got this :

 

Device: AZM(RA) Motor
    State: Running
    Model: NexStar GPS
    Address: 16
    Version: 3,00
    HwRev: 1

Device: ALT(DEC) Motor
    State: Running
    Model: NexStar GPS
    Address: 17
    Version: 3,00
    HwRev: 1

EXE Version: 2.2.5
DLL Version: 2.1.4

 

At last : results.

 

Now it means a few things :

1. My serial port is running

2. My cable is properly designed

3. The motor control board is responding

 

So it must come down to NexRemote. My Windows10 may not get along well with it. Any settings I should checked on Win10?

 

Thanks again for your precious help!     Francois



#15 Michael_Swanson

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Posted 10 September 2020 - 12:21 AM

Okay, the issue is you do need to update the MC firmware.  Upgrade to 4.06 and you should be good to go.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com



#16 pelfra

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Posted 11 September 2020 - 11:09 AM

Mike, could it be true? I'll have to wait till tomorrow to proceed with your advice. Many thanks.    Francois.  bow.gif



#17 pelfra

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Posted 13 September 2020 - 12:25 PM

VICTORY!

 

At My venerable C11 now talks to NexRemote. Everything is running smooth. Many thanks to all of you, Mike, Mark, Jim and others, who offered your time and expertise. At last, I'll be able to let this beautiful machine deliver what it i capable of.  

 

Francois.  bow.gifbow.gifbow.gif   waytogo.gif

 

ps : but don't go away, I do have some details that still elude me.      


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