St4 cable

[GaryCH]

Hi all, I've got a celestron avx mount and I want to make the cable to connect to a computer. I have a serial cable and usb adapter but I can't figure out how to wire up the rj12 type plug that connects to the mount!

Can anyone assist with this please?

Many thanks

Gary.

[gkec]

The st4 port is NOT a serial connection.  The serial connection (for my CG5 GT I assume the AVX is the same )  is at the bottom of the handset.

See here

http://www.nexstarsite.com/PCControl/RS232Cable.htm

[Cornelius Varley]

The ST4 cable isn't one you're looking for. The ST4 is used to connect the laptop to the autoguider port on the mount, not for connecting the handset to the laptop.

[seanpius]

Hi, the St4 port is to connect mount to guider..

[GaryCH]

Ok, thanks all.

So I've got a cable from my old autostar mount that has the serial one end and a four pin rj10 that physically fits in my nexstar handset on the other end. If I can confirm the wires are connected in the correct order, is that the right setup to use a webcam through my laptop on PhD to guide my mount with?

And if, in the future, I was to buy an auto guiding camera, would that connect directly to the mount via the st4 port?

Thanks for your help on this, I've heard stories about people frying their mounts circuits by doing this wrong, so I want to be 100% before I properly try anything!

Gary.

[gkec]

I haven't used PhD but I believe your setup is correct.  I have also read that people prefer to let PhD control the mount directly rather than via the cameras ST4 port which sort of makes sense. If you have control via the serial port why use another way of controlling the mount? The ST4 port doesn't use active input signals they just connect a signal from the ST4 port to one of the other wires to "nudge" the mount one way or another.   

The mount port for the handset is serial but uses TTL signal levels, 3-5V .  Shoving RS232 12V signals into it won't do it any good!

[GaryCH]

Ok great! I've reconfigured the serial lead for the handset as per the link above. I'll give it a try when I get a chance.

It seems a bit strange that it's only got 3 active wires in the setup - I was expecting 4?! I'll soon see, if it works I'll be very happy!

[gkec]

Ok great! I've reconfigured the serial lead for the handset as per the link above. I'll give it a try when I get a chance.

It seems a bit strange that it's only got 3 active wires in the setup - I was expecting 4?! I'll soon see, if it works I'll be very happy!

3 wires for serial is normal.  A common ground and transmit and receive.  If the signals were balanced then you would have signal pairs.

[GaryCH]

Well, I've spent the whole evening trying to get this working in my lounge!

Does it only control the one axis? I've got PhD and the relevant drivers for my mount and all seems ok, apart from the fact that it only seems to work on the east and west buttons. Is that right? Or have I messed something up? I checked and double checked my wiring so I think that's ok.

I've also got my Logitech quick pro 4000 connected and PhD has selected it, but I can't see any kind of image - even light differences etc as I would see in other software.

I guess these are problems for tomorrow night now, but any insight would be greatly appreciated, as always!

Thanks,

Gary

[GaryCH]

I found a very detailed walk through on this forum and I think I understand what do now. I also realised that I didn't connect the dec power cable late last night when testing, that just might be why PhD couldn't control the dec motor!

Thanks again for all the info [emoji106]

Gary.