Starlight Xpress SXVF-H16 - Manual (Page 19)

Handbook for the SXVF-H16 Issue 1 August 2006
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The accessory ports
The SXVF-H16 is provided with two ports for use with accessories. The Autoguider
output port is a 6 way RJ11 socket, which is compatible with the standard autoguider
input of most telescope mounts. It provides 4 active-low opto-isolator outputs and a
common return line, capable of sinking a minimum of 5mA per output. This socket
may be used for telescope control if the SXVF-H16 is employed as an autoguider, but
is primarily intended to be the control output for the optional add-on autoguider
camera head, available for use with the SXVF-H16.
The high density parallel port socket provides both control and power for the add-on
autoguider, but also includes a pair of serial ports for use with other devices.
Using the built-in serial ports
The SXVF-H16 incorporates two fast serial ports for use with external accessories.
The ports are available on 5 pins of the 18 way connector that is provided for the
autoguider and may be accessed by plugging in a ‘serial port divider box’. The divider
box and cables are available as an accessory and may be chained in series with the
autoguider cable, when the guider is in use, or may be used on its own.
The two serial connections are in the form of standard RS232 PC style plugs and
provide TX, RX and Ground connections at RS232 levels. Access is via commands
sent through the USB connection and, at the time of writing, is limited to any serial
controls that are provided by the SXV software. It is expected that many more
functions will be added as the software is upgraded.
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Using the add-on autoguider:
A very useful accessory is the add-on autoguider head, which takes its power and
control signals directly from the SXV camera, via the 18 way socket on its rear panel.
The autoguider is only 1.25” in diameter and has a video style ‘CS’ mount thread in
its nose, so video lenses may be attached. The guider may be used with either an off-
axis prism assembly mounted in front of the SXV camera, or with a separate guide
telescope, rigidly mounted alongside your imaging telescope. I personally use it with