LX200 guide cable connection

[beren]

Hi I recently got a Shoestring GPUSB guide port interface adapter for the CG5ASGT mount but i was just wondering if any LX200 owners have used it for the scope with the auto guider port. Normally I have just been using the supplied r232 cable for guiding etc but I saw over at the Cloudy nights Forums someone had posted a diagram with the GPUSB adapter set up with it plugged in the LX200's auto-guider port . Just curious to know if there would be a improvement or advantage with guiding this way ?

[rogerg (Roger)]

Interesting...

Normally I would say the advantage is that you don't need a computer in the loop. That is, to use the RS232 you'd usually have:

Camera -> Computer with some guiding software -> LX RS232 port.

Where as using the guider port you would have:

Camera -> LX Autoguider port.

I wouldn't expecta device that works in one, to work correctly in the other. I would expect the two ports have a different command set. But maybe not?

If you have had it running direct to the RS232 port until now, maybe the LX200 GPS is different to my LX200 in that respect, or perhaps the Shoestring GPUSB adaptor can handle either.. I'm not sure.

Don't know if that's actually going to help you at all

Roger.

[beren]

Thanks the LX200gps manual has no info in regards to this and i cant find anything on the net other then chat on the yahoo groups that it may lessen the interference .I tried it this afternoon and everything seemed fine with the scope communicating with guidedog & PHD guiding. Ive attached the diagram provided by a cloudy nights member ie; he has a classic LX { http://www.cloudynights.com/ubbthrea.../o/all/fpart/1}

[mick pinner]

hi Stuart, do you run Guidedog and PHD Guiding together for some reason or do you only use them individually?

[beren]

Individually Mick, I always seem to have trouble tweaking either on a given night

[AndrewJ]

Gday Beren

Just saw yr post
I dont know what the GPUSB device does but re

"Just curious to know if there would be a improvement or advantage with guiding this way ?"

The two std serial ports require the guiding software to post Meade compatible serial commands. The CPU in the scope then processes these as and when it can.
The Autoguider port is just 4 contacts that get pulled to ground to initiate guiding ( Mimicing ST4 compatible guiding )
Also, these ports are apparently on a low level interrupt, so get priority in handling by the CPU. Thus, if you use the guider port, it frees up a serial port from the PC.

Re Rogers comment
"I would expect the two ports have a different command set. But maybe not? "
As per above, the rs232ports require Meade protocol commands
The guider port will work using anything that can short the wires
( and even the tip of a breadknife qualifies for this )

Andrew

[beren]

Thanks Andrew