The computer controlled telescope can accept autoguider input via two methods:
1. LX200 protocol: scope.exe knows about the guiding commands available in the LX200 communications protocol. Simply hook up the serial port from the guiding computer via a null modem cable to the serial port being used as the LX200 communications port on the computer running scope.exe. Martin Niemi's superb quickcam autoguider will do this very inexpensively.
2. Relay box: The autoguider needs to supply a relay for each direction, or, a +5 VDC TTL signal for each direction, or, a serial connection sending LX200 protocol commands.
If using a relay box, wire the interface circuit such that when a
relay closes, a +5VDC TTL signal is supplied as follows:
If
using a control signal, tie the control signals so that the control
signal going to logical high raises the input voltage to a +5VDC
level as follows:
(this scheme mirrors the four direction buttons on the hand
paddle)
up or north: to pin 13 of the parallel port, down
or south: to pin 12 of the parallel port, left or counterclockwise:
to pin 10 of the parallel port, right or clockwise: to pins 13 and 12
of the parallel port.
Purchase a 2 female to 1 male phone wire adapter. Plug the male
side to the control board.. Plug the hand paddle to one of the
females. The other female will be for the ST-4. Purchase a phone wire
with a male plug at one end to plug into the 2 to 1
adapter at the
control board. At the other end of the wire. Install the correct
computer plug to connect to the ST-4. You need to install 2 small
signal diodes in two of the wires. Install the 2 diodes inside the
computer plug.
The wire assignment is as follows:
ST-4
action HAND PADDLE PARALLEL PORT
ST-4
pins
-----------------------------------------------------------------
+5v
white
n/a ----------------------- 11, 5, 14, 8
-Az
yellow
10 ----------------------- 10
+Az
green
12 ---------|<|----------- 4 *
+Az
black
13 ---------|<|----------- 4 *
-Alt
green
12 ----------------------- 7
+Alt
black
13 ----------------------- 13
*
-----|<|----- This symbol represents a diode and they are a must
for thing to work.
Both the hand paddle and the ST-4 can be
operated at the same time although conflicting simultaneous signals
can be sent to the PC in this fashion, resulting in unpredictable
actions.
1. Put the telescope control program hand paddle mode into one of the guide modes. Set the speed of the guiding corrections by adjusting the microstepping guide speed.
2. Orient the autoguider by rotating it so that the autoguider's up and down correspond to the telescope's autoguider.
3. Calibrate the autoguider.
4. Initiate guide corrections by the telescope control program by momentarily flipping the hand paddle mode switch to the left and then center the switch.
5. Start the autoguider.
All guide functionality continues to exist with the autoguider on. For instance, in guide+stay mode, flipping the hand paddle mode switch momentarily to the right will calculate drift, and null the telescope's drift. Immediately re-initiate telescope control program guiding by momentarily flipping the hand paddle mode switch to the left and then center the switch. In guide+record mode, a record is kept of the autoguider's corrections.
The hand paddle can continue to be used. Pressing a
direction button will add its guiding correction to the autoguider.
piggyback guide scope
off-axis guider
built-in guider chip ala ST7, ST8