User`s manual

Page 3
Is my scope mount compatible with this device?
Unfortunately, there is no universally used standard autoguider port interface. However,
many scope mount manufacturers do use a port that has become somewhat of a default
standard. This interface is characterized by a six-pin modular (RJ12) jack that has this
pinout (starting from the left as shown in this picture):
• (1) Open or sometimes powered
• (2) Common (ground)
• (3) RA+
• (4) Dec+
• (5) Dec-
• (6) RA-
Some manufactures refer to this as ‘ST-4 compatible’, referring to an autoguider that
was made by SBIG (Santa Barbara Instrument Group).
The important thing is that pin 2 is the common, and that the four direction control lines
come out on pins 3, 4, 5, and 6. The Shoestring Astronomy Guide Port Interface
Adapter does not connect anything to pin 1. Most autoguide software, such as
GuideDog, allows the user to configure which pin of the parallel port controls which
direction of movement, so the exact order shown above is not critical. Resistors internal
to the scope mount pull these inputs up to the internal power supply voltage.
Optocouplers, relays, or switches can be used to pull them down to the common pin.
This configuration is sometimes used for simple hand controller ports as well.
Consult the manual that came with your mount to see if the autoguider port or hand
controller port uses this configuration. If this information is not in your manual, contact
the manufacturer’s technical support department.
A note of caution on cables!
Shoestring Astronomy sells cables that are known to be compatible with this adapter.
You can make your own or buy them elsewhere, but be sure that the wires connect
straight through, i.e. pin 1 to pin 1, etc. Some cables change the order of the pins.
If you buy a cable from somewhere other than Shoestring Astronomy, or build your
own, make absolutely sure that it is wired correctly. Incorrect operation and
possibly damage to your mount’s electronics may result if the cable is improperly
wired.