Complete Confusion on ST-4 to Takahashi Temma2

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jeffweiss9
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Complete Confusion on ST-4 to Takahashi Temma2

Post by jeffweiss9 » Wed Jul 17, 2013 12:33 am

I have successfully used a GPCONV-TAK to convert the supposedly ST-4 compatible autoguider RJ-12 type cable from the SBIG ST-i autoguider camera to the EM-200 Temma2 6-pin mini-DIN connector that plugs into the socket on the Temma2 box. It works just fine.
However, I just purchased an Orion StarShoot Autoguider camera (SSAG) and tried the same GPCNV-TAK converter on the end of it's similar autoguider cable to plug into the Temma2. What I find with more than one software (TSX and PHD) is that the autoguider camera takes images fine but WILL NOT SEND MOVE COMMANDS TO THE MOUNT.
I discovered that the standard ST-4 pinout is quite different from the Tak socket pins:
-----------------------------
Pin standard Tak
1 NC NC
2 GND RA+
3 RA+ RA-
4 DEC+ DEC+
5 DEC- DEC-
6 RA- GND
------------------------------
So if the GPCNV-TAK converter makes that pin conversion, then why does it only work with the ST-i but not the SSAG cameras which both are supposed to be ST-4 compatible autoguider cables?
SHOULD THE GPCNV-TAK work with ALL ST-4 compatible autoguider cables ?? Or do I have some other problem with software settings or driver?
Thanks very much.
R/Jeff

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Re: Complete Confusion on ST-4 to Takahashi Temma2

Post by jeffweiss9 » Wed Jul 17, 2013 10:25 am

To clarify my confusion,evidently there is no ST-4 "standard" from finding the pinouts on the web for my Orion SSAG, SBIG ST-i and Takahashi Temma2. Even the original ST-4 pinouts are different from any of these:

Pin...........SSAG ..........ST-i ................Tak
1............. NC.............RA+.................NC
2..............GND...........DEC+................RA+
3............. RA+............DEC-................RA-
4..............DEC+..........RA-..................DEC+
5..............DEC-..........GND..................DEC-
6..............RA-...........NC...................GND

So I have the GPCNV-TAK converter which works fine between the SBIG ST-i and the Tak Temma2. Now I (probably) understand why using that cable with the SSAG will not send RA+ commands to the Tak mount which causes calibration to time-out for both TSX/CAO and PHD.

So my reformulated questions are: do you have a different converter to take RJ-12 with the SSAG wiring to the Tak Temma2? Or a different one that just converts SSAG ("standard ST-4"?) to SBIG ST-i ST-4, which I could then plug into the GPCNV-TAK to go to the mount? Or other suggestions to make this work ?

Thanks,
Jeff

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Re: Complete Confusion on ST-4 to Takahashi Temma2

Post by jeffweiss9 » Wed Jul 17, 2013 5:02 pm

HOLD THE HORSES. I apologize for posting incorrect information. Trying to
understand information on another' SSAG-Tak connection using the GPCNV-TAK after the GSUSB, I
reread the GPCNV-TAK manual more carefully and learned it also
requires STANDARD ST-4 going in which is where I've been plugging the
"Nonstandard" ST-i cable according to what I posted above. Confused by that
information, I just spoke to SBIG technical support (David) and he explained that, THE
ST-i Camera PINOUT IS ST-4 STANDARD (as with all SBIG cameras since the ST-4)
BECAUSE:

1) The ST-i is supplied with an RJ-12 CROSSOVER cable that has pins 1-6 going to
pins 6-1, which reverses the order of the pins going to into the GPCNV-TAK which
then does the correct pin conversion for the Temm2.

2) That still wouldn't match standard ST-4 in my table EXCEPT for the fact that
the signs are immaterial. All that matters, David said, is RA to RA and DEC to
DEC. The signs are figured out by the guiding software, apparently. So
disregarding the +'s and -'s in my table and reversing the order, then BOTH the
ST-i (with crossover RJ-12 cable) and the SSAG (with standard RJ-12 cable)
should be ST-4 standard compatible.

With the SSAG unable to move the mount with either TSX/CAO or PHD using different drivers and s/w, I think the most likely hypothesis for my problem is that the autoguider port on the SSAG camera is just defective.

On that last hypothesis, I intend to return my SSAG camera to Orion's Cupertino
store (down the road from me) as potentially defective and start again to try to make it work.

-Jeff

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Re: Complete Confusion on ST-4 to Takahashi Temma2

Post by dpanderson » Wed Jul 17, 2013 6:46 pm

Unfortunately like a lot of things in astronomy, there is no industry-defined standard. The so-called de-facto ST-4 standard looking into the autoguide port on the mount is shown in this document:
http://store.shoestringastronomy.com/gu ... cables.pdf

Sometimes confusion arises from which pin is called pin 1, since this is not standardized in any document either.

Furthermore, there is no standard for what is driving the other end of the RJ cable. We use the same pinout so that a cable wired pin 1 to pin 1 is used, thus if multiple cables are coupled together, the pinout doesn't keep reversing with each added cable. To the best of my knowledge, most other manufacturers of autoguide imagers use this same pinout, except for SBIG.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

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Re: Complete Confusion on ST-4 to Takahashi Temma2

Post by jeffweiss9 » Wed Jul 17, 2013 11:28 pm

Doug, et al.-
Ok,the replacement SSAG camera now works fine getting the relay signals to the mount with the SSAG standard cable (no crossover) going to the GPCNV-TAK
Sorry for all the confusion but I guess, at least, I learned something for all the effort.
-Jeff

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