SBIG and ZWO cables are diffent.

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Lawrence Lopez

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Mar 10, 2020, 12:49:12 AM3/10/20
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ZWO asi cameras will not work with a SBIG cable.
SBIG camaeras will not work with a ZWO cable.

Tony Carillo

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Mar 10, 2020, 4:52:10 AM3/10/20
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The SBIG cameras appear to be USB2 devices, ZWOs use USB3, so would that explain it?


Lawrence Lopez

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Mar 10, 2020, 8:58:11 AM3/10/20
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Oops. 

ASI guide cables and SBIG guide cables are different.

Sorry, I really need to quell my enthusiasm.

I tried using a SBIG cable between a Paramount ME and a ASI or Loadstar X2 camera and it did not work.


On Tue, Mar 10, 2020, 4:52 AM 'Tony Carillo' via Open PHD Guiding <open-phd...@googlegroups.com> wrote:
The SBIG cameras appear to be USB2 devices, ZWOs use USB3, so would that explain it?


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Michael 8554

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Mar 10, 2020, 3:55:23 PM3/10/20
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ST4 was supposed to be a Standard, but in practise manufacturers wired the 6 pin RJ plugs any old way.

So no surprise you can't swap a cable between mounts and cameras.

Michael
Wiltshire UK

Lawrence Lopez

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Mar 10, 2020, 4:06:15 PM3/10/20
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The original ST4 cable had 4 single pole double throw relay contacts.
Normally open and normally closed for each of  Dec and RA, plus and minus.
This ended up with a cable with a RJ12 6 on each end.

The guider cable we use today has 4 contact closures.
It has to get the return wire correct.
It has to get opposing pair of movement correct (RA+, RA-)
It does not have to get the sign correct.
It does not have to RA or DEC pairs in the right place.
These last two are figured out when it does the calibrationrun.

There is only two ways to wire a ST4 cable.
With a twist and without a twist.
So the pin out is either 1-1, 2-2, ... or 1-6, 2-6, ...
What completely messed me up was that both the Loadstar and the ZWO asi cameras didn't work.
But the SBIG ST402ME did work.
At which point I gave up assuming some metaphysical reason.
Later I figured it out.

Larry


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zhongchun ji

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Mar 11, 2020, 1:51:03 AM3/11/20
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Hi Lawrence, did you mean the ST4 came with ASI cameras that cannot work with your mount?

Lawrence Lopez

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Mar 11, 2020, 8:54:59 AM3/11/20
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No.  I mean that the sbig cable cable would not work with the ASI camera.

It would also not work with the Loadstar X2 camera.

I intend to try out a asi178 camera because it has smaller pixels which should work even better than the sbig ST-402ME with the 60mm f 4 guide scope I have.



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Lawrence Lopez

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Mar 11, 2020, 9:04:17 AM3/11/20
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No the zwo camera cable should work fine with the zwo and Loadstar X2 guider but it will not on the SBIG ST-402 CAMERA.

The SBIG ST-402 cable will not work with the ZWO or Loadstar X2 camera.

There only 2 kinds of cables like this.
One has a half twist one that does not have a half twist.





On Wed, Mar 11, 2020, 1:51 AM zhongchun ji <jizho...@gmail.com> wrote:

Greg McCall

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Mar 11, 2020, 6:12:30 PM3/11/20
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ST4 is not a standard.
It's just a name that people generalised and used over time.

Lawrence Lopez

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Mar 11, 2020, 9:39:30 PM3/11/20
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The ST4 had relay contacts and no modular connectors on it.

The thing we call a guide cable is a standard
but it doesn't seem to have much to do with the ST4.

My old byers mount had wires to connect to.
No modular connectors that I remember.

There are only two ways to make the cable  guide cable which we use nowadays.
The cable has 6 wires and they are basically a ribbon cable in a sheath.

So the only change you can make is to turn the connector 180 degrees.

So one kind of cable  is pins 1,2,3,4,5,6 connected to 6,5,4,3,2,1
The other kind  of cable is pins 1,2,3,4,5,6 to 1,2,3,4,5,6

You can plug either end into ether ended (end 1 to mount, end 2 to guider) or (end 2 to mount, and end 2 to guider).

RJ12 connectors were not associated with the ST-4 anyway.

Since I figured out how to use POTH to The Sky Controlled telescope I won't be using a cable unless it works better with a cable.
I'll be using  direct drive or pulse drive.

I have to see which way works the best.


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Greg McCall

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Mar 11, 2020, 10:16:50 PM3/11/20
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The ST4 was an SBIG device (Star Tracker version 4) and not a standard.

When the terminology was first used for the cable going to a guide port on early mounts, the ST4 actually had a 15 pin port and RJ12 on the other and was basically a shortened term for the cable going to the autoguider, even though later versions of the “Star Tracker” (star guider) eventually evolved to the RJ12 (both ends)

 

So it’s hardly a standard as the term. It’s just a label for a type of cable that has stuck over time and was not defined. Definition is what standards are about.

Even the use of the guide port has carried over from Star Tracker & Auto Guider to also include a port on a camera with some hardware/software to convert USB commands from a guider on an external computer (such as PHD2) to signals on a wired cable.

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Lawrence Lopez

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Mar 12, 2020, 12:14:26 AM3/12/20
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Thank you very much for the clarification.


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