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Equipment Discussions >> Mounts

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ur7x
sage


Reged: 01/08/12

Celestron Nexstar "AUX" port... Serial to TTL
      #5981908 - 07/20/13 07:48 PM

Here is what I have:
ASGT with an old 6" Newt (portable)
CGEM 9.25 OTA on a pier.

Here is what I know.
1) I know the hand controller port on the CGEM is wired the same as the AUX port (basically parallel connections).
2) I also know that the hand controller talks to the mount via a standard serial signal but at TTL (+/-5V) voltage levels.
3) I also have had great success using tools like "TheSky" to drive my mount via the RS232 connection at the bottom of the hand controller.
4) I also know that people have used the aux port building their own homegrown RS232-TTL conversion tools like this one:
http://www.ea4su.org/equipo/CelestronAS_PCinterface.pdf since Celestron discoed there version of the same a few years ago.

Here is what I would like to do:
I would like to have the hand controller run free of the serial to 4 pin dongle and instead use the AUX port to drive the mount remotely with my PC and tools like TheSky6/X

My question:
RS232 Serial (+/-12v) to TTL (+/- 5v) converters are basically very common and are dime a dozen gizmos... Would any decent RS232 Serial to TTL converter work? would something like this: http://www.ebay.com/itm/RS232-To-TTL-Converter-Module-COM-Serial-Board-MAX232...
do the trick?

Anyone done this?


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: ur7x]
      #5981932 - 07/20/13 08:11 PM

on which mount? I believe both the CGEM and ASGT/CG5 do not have a "PC port"

You can just use the PC port and the correct cable/adapter. If either mount does not have a PC port, then you can get the very hard to find Auxiliary Port Accessory Kit (part number 93965) mostly used for the CG5 mount. This takes the hand control port and makes it into 2 AUX ports and a PC port.

I am not sure if a 3rd party solution will work. Celestron, I believe. ID's each port as well as has some proprietary pinout with the wiring. You could probably trace it all.

More info here: http://www.nexstarsite.com/OddsNEnds/PortsCGEM.htm

At the bottom of the site, there is a link: Ken Hutchinson has put together a document detailing how to build an adapter that connects to the HAND CONTROL or AUX port and then provides a PC Port that works as described above.

I believe it is the same document you posted.


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: wolfman_4_ever]
      #5981974 - 07/20/13 08:36 PM

The Aux port is exactly the same as the HC port. Plugging a serial cable into an Aux port will damage computer or scope or both. What you are proposing will not work anyway. You have to have either the hand control, or at least its firmware running on a PC in the form of NexRemote to operate the mount, period.

You CAN operate the mount WITH NEXREMOTE without the HC by plugging the computer into a PC port. Unfortunately the CG5 doesn't have one, and Celestron no longer sells the electronics box, The Aux Port Expander, that provided one, but if you are handy with electronics you can make one with plans available on the Celestron ASGT Yahoogroup.

Edited by rmollise (07/20/13 08:37 PM)


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ur7x
sage


Reged: 01/08/12

Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: rmollise]
      #5982001 - 07/20/13 08:56 PM

Yes! that is exactly what I'm proposing...

The Celestron ASGT Yahoogroup home built PC Port expander (thats the first link in my post) looks to be just a powered RS232 to TTL converter.

My question is has anyone tried a commercial RS232 to TTL converter rather than building one from scratch... as per the Celestron ASGT Yahoogroup plans?

My goal is not to delete the hand control but to use the AUX port (via a coverter) instead of the dongle on the bottom of the hand controler.

And to the second poster, yes, neither mount has a PC port, but I'm focused on using the Aux port of the CGEM as a PC port.


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: ur7x]
      #5982112 - 07/20/13 10:11 PM

Why exactly would you want to do that? It won't work. You can use a PC port type connection to operate the mount with NexRemote (you must use NexRemote), or you can run the mount with the hand control and send it on go-tos with an astronomy program through the serial port on the base of the HC.

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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: rmollise]
      #5982146 - 07/20/13 10:38 PM

Howdy Uncle Rod...

Actually, I am looking at this same issue. For me, it is the "untidy" nature of running the computer connection down and around to the bottom of the HC.

For me (or to me....), it would be much "cleaner" cable wise, to have a cable go directly to the mount base, as with the power cable, and guiding cable.

I am very interested in this thread, and am also looking for a solution.

The use of the HC or Nexromote is not the issue (at least to me).


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ur7x
sage


Reged: 01/08/12

Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: rmollise]
      #5982152 - 07/20/13 10:42 PM

Lots of reasons.

In somewhat reverse order:

First of the dongle on the bottom of the hand control is awkward and looks ugly.

Second it is a bear to connect and disconnect.

Third as the telescope slews it drags the hand controller around with it... that is bad, having it move the hand controller plus a dongle, connected to a cable with DB9 ends is even worse. Two curly RJ12 cables would be much more engineering elegant. Not to mention less likely to unplug themselves in the middle of a remote skew.

Fourth (and this is probably the main reason I'm looking into this) I'm trying to simplify setup, take down and storage, since most of this will happen in the cold, in the dark, likely when I'm tired, frustrated and in a hurry to get to bed. My goal was to unplug: power, the HC, an RJ12 line that goes back to the PC (running Nexremote or TheSky) and the USB line that goes to the camera. Power, and the two data lines (RJ12 and USB) are on the pier so the would be easy to connect and disconnect. And they are short, light, elegant and less likely to be pulled out in a slew (I've done this a few times already)

Are we certain that the ASGT homebrew solution won't work? What if I found a NOS or used 93965? Can't I have that in the AUX port and use both the hand controller and "TheSky" or Nexremote? Wasn't that how it was to be used?


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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: ur7x]
      #5982180 - 07/20/13 11:09 PM

Howdy ur7x...

From everything i have read.... the 93965 was intended to do it all. It was designed for the CG5... which had no aux port. The 93965 would plug into the HC port, and provide two aux ports (HC and GPS), and a PC port (which is what we are looking for.

I too have a CG5 and a CGEM. With the CGEM, it DOES have an aux port (wired in parallel with the HC port). The homebrew box - plugged into the aux port, is intended to provide the computer interface.

I have been searching and searching. Cannot seem to locate a used 93965. Wonder why they stopped making them ?? Or why there are not any used ones out there looking for a home.

I am thinking i will have to build one of the homebrew units. Might look at your circuit board also, and check signals. Have not done that yet.


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SkipW
sage


Reged: 02/03/11

Loc: Oklahoma, USA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: ur7x]
      #5982211 - 07/20/13 11:44 PM

Quote:

...Third as the telescope slews it drags the hand controller around with it...




Wait... what? The HC for my CG-5GT (ASGT) plugs into a panel that doesn't move when the telescope does. If you want to use the HC at the eyepiece, you do have to take it out of its cradle and move around, and if the serial cable is attached, that's a nuisance, but it HC isn't dragged around by the mount.


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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: SkipW]
      #5982255 - 07/21/13 12:29 AM

Hi SkipW...

Yup... you got it right.
BUT....
The CGEM body, where the cables plug into, does move....


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ur7x
sage


Reged: 01/08/12

Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: dmdouglass]
      #5982277 - 07/21/13 12:57 AM

Quote:

Howdy ur7x...

From everything i have read.... the 93965 was intended to do it all. It was designed for the CG5... which had no aux port. The 93965 would plug into the HC port, and provide two aux ports (HC and GPS), and a PC port (which is what we are looking for.

I too have a CG5 and a CGEM. With the CGEM, it DOES have an aux port (wired in parallel with the HC port). The homebrew box - plugged into the aux port, is intended to provide the computer interface.

I have been searching and searching. Cannot seem to locate a used 93965. Wonder why they stopped making them ?? Or why there are not any used ones out there looking for a home.

I am thinking i will have to build one of the homebrew units. Might look at your circuit board also, and check signals. Have not done that yet.




I took a long hard look at the ASGT "Homebrew" circuit. It is very elegant, it takes 12V from the mount to power itself and it uses a second IC to buffer the first IC that coverts 10-12V RS232 to 3-5V TTL. The second "buffer" IC is wired in a way that protects the mount (but not the PC..hmmm...). An average Joe would never do that if you knew that your were using a PC to drive this... Unless you were worried about warranty claims on your mount. It looks what I would describe as a "commercial grade" circuit, not at all homebrewed.

The way that the connectors and IC's are numbered it would also have me conclude that this was "designed" with more than a little help from Celestron... .. "copied" might be a more accurate verb than designed. I bet if we ever find a 93965 and open it up you will find 2ICs and a voltage regulator that will look a lot like the homebrew (if not exactly the same).

For the ~$10 that the digikey parts will cost... and given I have a bunch of guys at work who would rather solder for the boss than do their real job... I think I'm going to build the so called "Homebrew" and then see if TheSky6 will drive the mount through the AUX port.

If this works... and I bet it will... I will post back my results... Its gonna take a few weeks.

Have you tried using TheSky6 (or X) though the "dongle" yet? It is interesting that NexRemote requires you to basically re-do the alignment procedure.. But TheSky seems happy just to grab the mount and start moving it around.


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: dmdouglass]
      #5982278 - 07/21/13 12:58 AM

to my knowledge everything uncle rod has said as well as others is true, there is no direct HC replacement for nexstar scopes like there is for the synta synscan mounts (EQMOD) the only way a nexstar mount can work with or without a HC via a PC is with nexremote software. you can run the mount via it though the HC PC port or connected directly to a PC port (provided the mount has one on it directly) but when doing so the HC is basically just being used as an interface and is not usable.

heres a great bubble chart showing how things can connect to basically any nexstar mount/scope

http://www.nexstarsite.com/download/NexStarCablingV5.pdf


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: frito]
      #5982281 - 07/21/13 01:01 AM

i will note however when i say run the mount, i mean align it and get it setup. using the nexstar ascom drivers any ascom compatible program can operate the mount once its setup via the same serial interface nexremote runs from.

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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: frito]
      #5982285 - 07/21/13 01:06 AM

ur7x you will not be able to align the mount without nexstar firmware. its a hard requirement. see that chart i posted above. in order to even use a PC program (or tablet/phone app) to control the mount its a hard requirement to have used the hand control to set it up initially and then connect through the HC to the PC.

EQMOD for synscan is what you are trying to do but the problem is nobody has made an EQMOD that can run nexstar scopes and mounts, EQMOD is basically a custom full on firmware replacement, thats why it works the interface is not the main problem your facing, its the fact that there is no software besides nexremote that can operate the mounts with full access and control, making such software would probably require someone from celestron to leak the required info needed to make it possible (likely what happened with synscan and thus EQMOD was born but i'm just guessing)


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: frito]
      #5982293 - 07/21/13 01:11 AM

if you really want to get into modding mounts to run them that way it may be possible

http://eq-mod.sourceforge.net/reqindex.html

info is there, older simpler motorized only mounts have been converted before, i'm guessing without any research that MC board needs to be scrapped and replaced by home made electronics if done so.


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: frito]
      #5982312 - 07/21/13 01:25 AM

you still have to run nexremote or the hand controller for theskyx to work.

The alignment is kept in the HC.. that's why you need to align with either nexremote or the HC.. if you use nexremote and keep the HC plugged in, if you do everything with nexremote, the HC sits there saying "press enter to begin alignment". When I do a factory reset, I do it both in nexremote and on the HC.

As Frito said, you need to have nexremote do some sort of alignment before theskyx will work. Either 2 star or 1 star or quick or last alignment. If not, theskyx, upon connection, will say "telescope not aligned".


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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: wolfman_4_ever]
      #5982368 - 07/21/13 02:19 AM

I think several people are not understanding the op's effort. Either that, or i don't understand it.

My issue is not he HC. It is the cabeling.

As to the TheSkyX question... yes, when i connect the PC to the HC, I can run either the CG5, or the CGEM. Both the HC and the software work, together.

In my case, i am NOT trying to get rid of the HC... i just want to be able to use the PC (after alignment), and have neater cabeling.

UR7X.... is that your goal also ??


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: dmdouglass]
      #5982378 - 07/21/13 02:31 AM

if that is your goal then why not secure your serial cable going to the HC to the HC's coil cable and then down the mount.

cabling issues don't require interface modules, they just require a bit of work cleaning them up, i made my PC interface cable from a phone handset cord spliced into a serial cable, if i wanted to have it so the HC and PC cord were tied together and still worked as intended all i'd need to do is tie strap some points together and call it a day. if your mount has a PC port on it already like the CGEM then its even simpler.


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jrcrillyAdministrator
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
Re: Celestron Nexstar "AUX" port... Serial to TTL new [Re: dmdouglass]
      #5982379 - 07/21/13 02:31 AM

Quote:

In my case, i am NOT trying to get rid of the HC... i just want to be able to use the PC (after alignment), and have neater cabeling.




As has been stated, the only way to talk to the mount through the mount's PC jack is by bypassing the handbox and using NexRemote instead. That jack doesn't talk to the handbox so when using it the handbox alignment is irrelevant and unavailable. It looks to Nexremote for all that stuff.


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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Celestron Nexstar "AUX" port... Serial to TTL [Re: jrcrilly]
      #5982394 - 07/21/13 03:02 AM

Your post:

Quote:
--------------------------------------------------------------------------------

In my case, i am NOT trying to get rid of the HC... i just want to be able to use the PC (after alignment), and have neater cabeling.

--------------------------------------------------------------------------------

As has been stated, the only way to talk to the mount through the mount's PC jack is by bypassing the handbox and using NexRemote instead. That jack doesn't talk to the handbox so when using it the handbox alignment is irrelevant and unavailable. It looks to Nexremote for all that stuff.

--------------------

Ahhhhhhh. Hold on one. That is NOT correct.
The PC software CAN connect via the serial port on the HC. As I (and others) have said, we do that already.

NexRemote is a nice PC interface. It puts a virtual HC on the screen. But i don't use that. I use TheSkyX, AND/or the HC.

Yeah.... I run the serial cable from the mount (area), down through the HC cable and to the HC. That is working.


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