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CGEM Mount & Nexstar via Ethernet->Serial adapter

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#1 Gert

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Posted 29 January 2011 - 05:12 PM

Hello All,

Our group is looking to do remote control of a CGEM mount beyond the limit of USB. (We need about 180ft). Wifi doesn't work because there are metal walls in between.

We think about using a long Ethernet cable with a serial adapter like this:

http://www.neteon.ne...-3-13-365/GW212

Ideally there should be no issue and the driver for the adapter should just create a new virtual COM port in the PC (windows, not linux). The planetarium program should then connect to that port and talk to the NexStar controller at the mount 180ft away.

Now we all know that astronomy gear is sometime picky about drivers and adapters. So want to ask the group if anybody has already tried a setup like this and can report the results.

Your feedback is most welcome.

Clear Skies,
Gert

#2 PHampson

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Posted 29 January 2011 - 06:53 PM

I don't know about that particular unit but I use one of these -
http://www.cooldrive...b20ovipne4.html

I use it to control the mount, my SBIG cameras, and my motorized focuser all at the same time over one ethernet line. Pretty easy to set up and works fine.


Paul

#3 Peter in Reno

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Posted 29 January 2011 - 07:17 PM

This is the first time I have seen a device supporting USB 2.0 with Ethernet cable for less than $100. Thanks for posting the link.

Peter

#4 WalleyeRed

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Posted 30 January 2011 - 11:34 AM

I thought the CGEM used RS232 serial connection to control the unit, not USB? I'm sure someone will clarify that, but... I do a similar remote control setup with my Nexstar SE, although not nearly as far as you are talking about. If you use high quality shielded twisted pair (STP) Ethernet cable you could get that distance without any repeating device. I've heard of people using serial cables to 500 feet with quality cable. Then you would just need to crimp/solder the correct pins to the suitable gendered DB9 to connect to your PC or USB-Serial adapter.

#5 rmollise

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Posted 30 January 2011 - 12:58 PM

Hello All,

Our group is looking to do remote control of a CGEM mount beyond the limit of USB. (We need about 180ft). Wifi doesn't work because there are metal walls in between.

We think about using a long Ethernet cable with a serial adapter like this:

http://www.neteon.ne...-3-13-365/GW212

Ideally there should be no issue and the driver for the adapter should just create a new virtual COM port in the PC (windows, not linux). The planetarium program should then connect to that port and talk to the NexStar controller at the mount 180ft away.

Now we all know that astronomy gear is sometime picky about drivers and adapters. So want to ask the group if anybody has already tried a setup like this and can report the results.

Your feedback is most welcome.

Clear Skies,
Gert


Why not use plain, old RS-232?

#6 Gert

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Posted 30 January 2011 - 01:45 PM

Hi All,

Thank you all for the feedback.

To address some confusion coming into the discussion.

The proposed device is a Ethernet to serial adapter. Not a Ethernet to USB adapter. Peter commented on his use of Ethernet to USB adapter which was unrelated to the original question.

We plan to have an Ethernet switch at the mount and also have CCD camera control over the same line, using Ethernet to USB adapter technology. Thus a plain serial connection is not feasible. Sorry that was not indicated clearly in the original post.

Clear Skies,
Gert

#7 Peter in Reno

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Posted 30 January 2011 - 03:57 PM

How about using Ethernet to USB box as described earlier and then use one USB port and use USB to serial adapter (RS232) to control the scope? The remaining USB connections for camera, autoguider and others like focuser motor.

Peter

#8 Midnight Dan

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Posted 30 January 2011 - 04:14 PM

As Uncle Rod says, why not just use a long serial cable (RS 232)? The maximum length if you're using 19,200 baud rate is 50 feet, but astro gear rarely runs at that high a speed. If you use a lower baud rate you can go huge distances and the cable is cheap!

19,200 baud - max length = 50 feet
9,600 baud - max length = 500 feet
4,800 baud - max length = 1000 feet

If your computer doesn't have a serial connection, use a USB to serial adapter and then a long serial cable to the mount.

-Dan

#9 Peter in Reno

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Posted 30 January 2011 - 04:33 PM

The nice thing about ethernet is long distance and only one cable between computer and scope equipment. The Ethernet box is what I was looking for controlling not just the scope but camera, autoguider and focuser motor. Having one cable is less messy to deal with at long distance.

If the original poster decides to expand into astro-photography remotely, the Ethernet to USB box should help.

I don't know if the USB port of any computer can drive a USB to serial and then long serial cable due to limited current drive of USB port at the computer since the USB to serial adapter is powered by USB port. Also the USB to serial adapter may have to up-convert from 5V to +/-12V since RS232 requires +/- 12V and USB port at the computer may not be strong enough to drive the USB to serial adapter for long distance.

Which why I really like the Ethernet to USB box. You can have very long Ethernet cable, Ethernet to USB box near the scope/mount and a short USB to serial adapter connection to the mount.

Peter

#10 WalleyeRed

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Posted 30 January 2011 - 05:17 PM

How about using Ethernet to USB box as described earlier and then use one USB port and use USB to serial adapter (RS232) to control the scope? The remaining USB connections for camera, autoguider and others like focuser motor.

That seems to make the most sense if I am understanding his situation whereas there is only one ethernet cable run and no option to run any other cables. Get a multiport USB over Ethernet box and then several cheap Prolific or Sabrent(or whoever) USB-Serial adapters for control of any RS232 devices such as the CGEM, etc.

I suppose the OP could use the serial port server that he posted, but if there is already going to be a USB over Ethernet device, it seems like an unnecessary expense. Then again, maybe I'm still not seeing the big picture in which case I'll just shut up :crazy:

#11 Gargoyle

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Posted 30 January 2011 - 05:52 PM

I like that Peter. Extra ports for the Camera, etc..

I have a long Ethernet from my home ofice computer to a location near my mounted MI-250. My configuration with this has been to have my laptop co-located with the mount and remote desktop in to my home office computer. Barring the initial startup and focusing, the ethernet to USB box with a USB to serial adapter takes care of the Gemini connection and removes the laptop. So that is a big win.

As well, this setup will also work with my CGEM. I usually set the CGEM up about 30 feet away from the MI-250, so running a patch ethernet cable from the fixed location while using the same configuration is easy.

Can't wait to give this a try.

Jerry

#12 Peter in Reno

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Posted 30 January 2011 - 07:01 PM

Also, the Ethernet to USB box supports wide input power range: DC 9-30V. That means I can use my marine 12V battery which I always use in my backyard for mount, camera and focuser motor because my house A/C power gets enough brown outs/outages, shuts down my mount/equipment and ruins my night. Another big plus for this box.

Peter

#13 Gargoyle

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Posted 30 January 2011 - 07:40 PM

I just ordered the unit from Cooldrives. I'll post back to this thread on how it functions when I receive it.

Jerry

#14 PHampson

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Posted 30 January 2011 - 09:46 PM

I've used my CG5ASGT successfully with a Prolific serial-to-usb adapter hooked into the handset with the Celestron cable - just like updating the firmware. You just have to first set up the server with its MAC, set the ip addresses (mine uses 192.168.3.22 so I set the ethernet card to 192.168.3.1 as a gateway), load the drivers for whatever you're using which it should find with PnP if you've used them on the computer before, and then find the COM port the serial-to-USB is using (mine uses COM6 for some reason) to set whatever control software you're using (TheSky works so I presume NexRemote will). After the first setup all you have to do is plug it in and go. Mine's actually a little older model than the one I linked - the new one looks more robust. It's worked well for me running off AC power - haven't tried a battery.

Paul

#15 Gert

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Posted 31 January 2011 - 03:04 AM

Hello All,

Thanks again for the additional discussion.

The plan is to deploy the Ethernet cable first. Then multiple options are possible at the mount location.

A path from Ethernet to USB to serial is possible. It is however one additional interface/translation with a chance of software/driver incompatibility/failure.

A direct Ethernet to serial adapter appears preferable at this time. (to serve just the CGEM mount)

This does not exclude that in the future an Ethernet to USB adapter for CCD camera use could be added. An Ethernet switch at the mount could serve multiple devices.

The original question was if anybody has already tested Ethernet to serial devices with a CGEM mount. (seems not)

Clear Skies,
Gert

#16 PHampson

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Posted 31 January 2011 - 11:59 AM

Sorry for confusing the issue. I just wanted to offer a solution that's worked well for me and is in the same price range as what you asked about. Just MHO, but the price on the unit you asked about seems a little steep for just a one port connection and would waste a lot of available ethernet bandwidth.
The advantage of deploying a USB based unit at the mount is that most of accessories you'd want to link to are probably already available as USB. Using an ethernet switch at the mount would require another adapter or adapters to connect other devices anyway. Anyway, my Prolific-chip based serial-to-usb hasn't shown any hint of a problem yet (knock on wood), FWIW.
Oh - if you don't already have an ethernet switch and still want one, I recently switched my home network to wireless and have a Linksys EZXS88W 8-port switch going to waste - ultra-cheap, just PM.
Good luck with whatever you go with.


Paul

#17 Gargoyle

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Posted 31 January 2011 - 02:50 PM

Paul,

Can I PM you on this?

Jerry

#18 PHampson

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Posted 31 January 2011 - 04:28 PM

Sure.


Paul






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