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Controlling a mount through a guide port

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#1 jbalsam

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Posted 29 March 2013 - 10:10 AM

I want to be able to point my CGE using Maxim via the guide port on my QHY5. In Maxim, if I go open the Observatory window, go to the Setup tab, and under Telescope I click Options and then Choose, I see an option for "QHY_CMOS Guide Port." This is how I got the idea that this might be possible. However I haven't been able to actually get it to work. When I click Connect after selecting the guide port nothing happens, and when I issue a move command Maxim says it can't communicate with the mount. I'm able to guide the mount perfectly well when the camera is connected to PHD, so I assume what I'm talking about is possible.

Has anyone done this? Any tips for getting it to work?

Here's a screenshot of what I'm talking about in maxim:
https://docs.google....dit?usp=sharing

#2 Hilmi

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Posted 29 March 2013 - 10:16 AM

To my understanding, if you where to use the guide port for slews it could take you as much as 5 hours to slew to a target. This is due to the fact that guide port will most likely be performing at something like 0.5 X siderial.

#3 jbalsam

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Posted 29 March 2013 - 10:21 AM

Oh okay. So the guide port is hard-wired to run Move commands at that slower speed? Well... maybe I just have to suck it up and buy a GPUSB.

Wait a minute. My laptop has an RJ-11 jack with two pins... Can I run that directly to the mount's "computer" port? Or does it need the full six pins?

#4 jbalsam

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Posted 29 March 2013 - 10:30 AM

Nevermind... answered my own question. ST4 ports use pins 2 through six. No dice...

It also appears that what I thought about the GPUSB was wrong. Apparently it's only for guiding, not for fast slews.

Some reading has informed me that I need to get a USB to serial adapter, and then an RJ45 to serial cable to go from my CGE to my computer. Has anyone reading done this?

#5 orlyandico

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Posted 29 March 2013 - 11:54 AM

get an FTDI adapter from ebay.

then get the Celestron Nexstar serial cable. It connects to the jack on the base of the handset.

this will allow you to do full computer control of your CGE, and also allow you to flash the motor and handset firmware.

#6 mclewis1

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Posted 29 March 2013 - 12:56 PM

1) Serial RS232 connection via the port on the base of the hand controller - Mount control from a planetarium/mount control app and the ability to autoguide via pulse guide commands. If the device drivers used are capable then you can share the port between the two apps (control and autoguide). The cable is the Celestron #93920 serial HC cable.

2) Serial RS232 connection via the PC port on the mount - Mount control is from the NexRemote app and/or via planetarium app through the virtual serial port in NexRemote, or an autoguide app via that virtual serial port ... but NexRemote must always be present to use this PC port interface. The cable is the Celestron #93922 (Ethernet RJ45 patch cable with a DB-9 adapter).

3) ST-4 connection via the Autoguide port on the mount - Signals/cable must be ST-4 compatible, so either off of an autoguide port on a camera or via a USB or parallel port conversion product (the GPUSB or GPINT-PT) when connected directly to a PC. The cable is a 6p6c (6 pin 6 connector) with RJ11/12 connectors. This interface does not know anything about move or high speed slew commands ... it's simply 4 direction lines (NSEW) that the controlling interface takes to ground to move in the required direction ... it's intended only for fine mount movements for autoguiding.

More info on the mount's connectivity options - www.nexstarsite.com

#7 jbalsam

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Posted 29 March 2013 - 02:05 PM

Thanks Mark. I didn't realize I needed to download NexRemote. That saves me some time.

And thanks Orlando. I picked up a usb/serial adapter, and I think I'll make the cable I need from the directions on nexstarsite.

I'll let you know how it goes.

#8 jbalsam

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Posted 29 March 2013 - 04:45 PM

Success. Got the proper cable made (thanks to great instructions from nexstarsite), got NexRemote (thanks Mark), downloaded the requisite celestron ascom drivers, and everything works like a charm.

I'm actually quite surprised that it worked without a lot of fooling around. It seems like it usually takes me a few hours of debugging to get new things to work.






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