How to connect an ST2000xm to a Gemini

JohnH · #1 13-10-2011, 02:00 PM

This is driving me nuts! I have a recently acquired ST200XM with a CFW8 fitted and need to connect it to my Losmandy G11G mount. The Gemini is a G1 but of the newer type with a rocker switch and DIN plugs for the motors.

The FW connects to the ST2000 with a plug that also has an RJ45 type socket (see attached image). I assumed that was the correct place to connect my guide cable. I tried it that way but it does not work, in fact the Gemini gives an alarm sound on power up if I connect that way.

So there is an alternate - that is to use the supplied mutiple adapter cable and the 9pin to RJ cable. (see photo).

That does not work either so now I am stumped.

The phone type guide cable I have is straight through (I used to connect a QHY5 to the Gemini with it so I know it works!) - should they be a different pattern, if so what?

Poita (Peter) · #2 13-10-2011, 02:19 PM

Does the QHY5 still work with it? Might be worth checking first if you can, to make sure nothing went bang.

mill (Martin) · #3 13-10-2011, 02:28 PM

John this is a good read and has the pin outs in appendix A.
You might need a relay box

http://www.ruf.rice.edu/~ruco/manuals/ST-7XE%20Manual.pdf

Have fun reading

JohnH · #4 13-10-2011, 02:36 PM

Thanks guys but....

Yes the qhy5 works....And NO I do not need a realy box according to the manual :

IMPORTANT:

There are two different versions of the Gemini Autoguider port hardware. The versions can be distinguished by the type of connectors used for the motor cables. The older Gemini version uses RJ-45 modular connectors, and the newer version uses 6-pin DIN connectors. The primary difference between the versions is that the older version does not directly support autoguiders with TTL output, but the newer version does.
Both versions of the Gemini Autoguider port are plug compatible with SBIG model ST-4 and STV autoguiders.

and mine is the new style Gemini.

mill (Martin) · #5 13-10-2011, 02:40 PM

Then you better measure your guide cable or borrow one.
If that doesn't work, it could be that the camera itself is faulty (hope not).
Just read that the qhy works with the cable

JohnH · #6 13-10-2011, 02:50 PM

Am I reading this right. (see attached) to me it seems straight through is right but the SBIG put 12V onto pin1 and the Gemini sees that as an alarm trigger (it is suggested it can be used for shutter control in the manual).

So I need to cut the line to pin1 to make it work?

If so I cannot believe I am the first to hit this issue....

JohnH · #7 13-10-2011, 03:48 PM

Light Bulb!

I think I must reverse the cable pins - the QHY5 and SBIG camera socks are opposite according to some posts on Cloudy Nights...

bert (Brett) · #8 13-10-2011, 04:16 PM

The qhy5 and sbig cables are opposite. One is straight and one is reversed. Been there done that..... pulled my hair out. Didnt blow anything up, fortunetly for me!

There is 6 cables in the plug. In no particular order are:

1 common 12v negative, the 4 directional wires, and sbig cameras supply a 12+ down the wire left over. Not sure about your camera, but the st402 has a jumper that can be inserted or removed to suplly the 12v +. My st4000xcm supplies the 12v, and I havent installed a jumper in that camera.

The 12v positive is used to used to fire the relays on the sbig relay box, to isolate the signals from the mount to the camera, which can cause issues with some mounts, like the earlier geminis and AP's.

Brett

JohnH · #9 13-10-2011, 08:30 PM

Yup that was it the guide cable works now...