Appendix B Ultima 2000 Communication Protocol
100
Commands
The commands all start with a capital letter indicating the type of request, and then any data necessary for
the request. All letters must be upper case.
To activate a command press return. To nullify a command, press the “delete” button on the computer
keyboard. So, if you partially type in a command and decide you made a mistake, press “delete” and a new
line will appear but the command will not be sent to the telescope.
Here are a list of the commands and their functions.
Note: All the numbers unless otherwise stated are written in hexadecimal.
Command Name
Description
PC Command
Return Message
PCALIGN
“F” is the command followed by the RA
and DEC 16-bit angles written in
hexadecimal. Use this to perform a star
alignment operation. The return message is
a warp factor in decimal form.
F4321,8765
-23.1#
PCCANSLEW
Cancels a slew that is in progress
M
#
PCGETTRACK
These are the current tracking rates for the
alt and az axes. The values are in
hexadecimal. The displayed value “x”
indicates that the telescope is moving at a
rate of x/65536 tracking encoder ticks per
millisecond. There are eight tracking ticks
per tracking motor shaft revolution.
U
1234,5678#
PCCSETTRACK
Set tracking rate for azimuth axis and
tracking for altitude axis. Sidereal tracking
rate is about hex 0800. “T” is the command
followed by the azimuth and the altitude
values.
T1234,5678
#
PCLOOKUP
Return database info on current object.
D
object name, constel,
description, MAG#
PCECHO
This command causes the telescope to
return the character it was sent. This
command makes it possible for the PC to
know that communication between the PC
and the telescope is synchronized.
Kx
x#
PCGOTOALTAZ
“A” is the command, the relative
coordinates follow. Az is first; in this case
az is hex 12AB, alt is hex 4000. These are
16-bit angles. These are Alt-Az positions
relative to the downstops. They are not
actual Alt-Az coordinates.
A12AB,4000
#
PCGOTOCORRALTAZ
“B” is the command, the relative
coordinates follow. Az is first; in this case
az is hex 12AB, alt is hex 4000. These are
16-bit angles. This command applies the
B12AB,4000
#
