Appendix B Ultima 2000 Communication Protocol
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APPENDIX B - ULTIMA 2000 COMMUNICATION
PROTOCOL
You can control the Ultima 2000 telescope with a PC. You use Terminal under the Accessories Menu in
Windows. The settings needed to allow your computer to communicate to the telescope through Terminal
are shown in the figure below. Communication with the telescope is via an RS-232 port running at 9600
baud, 8 data bits, 1 stop bit, no parity, and no flow control.
The cable required to interface to the telescope has an RS-232 male plug at one end and a 6-pin telephone
jack at the other end. The wiring is as follows:
•
Green wire to pin 2
•
Yellow wire to pin 3
•
Red wire to pin 7
•
Black wire to pin 8.
Depending on the configuration of the serial interface on the PC, it may be necessary to get an RS-232
wiring box and attach male pin 4 to male pin 8 and male pin 6 to male pin 20. The telescope neither
monitors nor sets Data Terminal Ready or Data Set Ready. Similarly, for Ready to Send and Clear to Send.
What this means is, some computers send 5 volts over a line to tell the device it is trying to communicate
with that it is on. These computers would also expect to receive a 5 volt signal coming back to them so they
know the device they are trying to communicate with is on. The Ultima 2000 does not send or monitor 5
volt signals. If a PC requires these signals, it is necessary to feed the signals provided by the PC back to the
PC.
