From: Milton Aupperle <milton@outcastsoft.com>

Date: July 7, 2007 8:34:23 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] guiding with Astro IIDC

Phil;

On 7-Jul-07, at 8:03 PM, Phil Houston wrote:

Milton,

Again, thanks.  I do not know the ST-4 protocols and just assumed it to be compatible because it worked when plugged into the StarlightXpress St-4 port on their STAR 2000 guiding system.  This is most likely a hack, but since I paid the manufacturer to perform it, the warranty is still good!  Looking at the Shoestring Astronomy site I found some info pertaining to controller mods. 

http://store.shoestringastronomy.com/downloads/HCModGuidance.pdf

Schematic GP1 seems to apply to the controller I'm using in so much as the output pins from the GPUSB sinks (grounds) when activated.  This is exactly what happens when I press a button on the Powerguide controller.  Grounding the pin or pushing the button activates the circuitry and moves the scope.  No external relay box is required.  The longer the pin is grounded, the further the scope moves in that direction.

That is how the ST-4 works and how I hacked my old Orion EQ3/2 hand controller to work with the GPUSB and ActiveWire board too. However the pins that the GPUSB drives up or down have to match up properly with what pins on the hand controller need to be. For example RA+,RA-, Dec+ and Dec- on the GPUSB to your hand controllers pins.

Now, I have no clue as to what signals go into the GPUSB from the computer but, could it be possible for Astro IIDC to send the appropriate signals to operate this kind of controller as an option?  Maybe in version 4.x ?

There really is nothing on my end to do. I tell it to close a relay, it closes that relay and if I tell it to open a relay, it opens it. So  if you don't have the two pins for +/- RA movement on the Questar Guider connected to the two pins  +/- RA for the GPUSB - then nothing happens when I close the relay to move left or right.

HTH..

Milton Aupperle