Celestron NexStar 8i - Manual (Page 55)

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A A p p p p e e n n d d i i x x D D - - R R S S - - 2 2 3 3 2 2 C C o o n n n n e e c c t t i i o o n n
You can control your NexStar telescope with a computer via the RS-232 port on the computerized hand
control and using an optional RS-232 cable (#93920). Once connected, the NexStar can be controlled using
popular astronomy software programs.
Communication Protocol:
NexStar-i communicates at 9600 bits/sec, No parity and a stop bit. All angles are communicated with 16 bit
angle and communicated using ASCII hexadecimal.
Description PC Command ASCII Hand Control Response Notes
Echo Kx X# Useful to check communication
Goto Azm-Alt B12AB, 4000 # 10 characters sent. B=Command,
12AB=Azm, comma, 4000=Alt. If
command conflicts with slew limits,
there will be no action.
Goto Ra-Dec R34AB, 12CE # Scope must be aligned. If
command conflicts with slew limits,
there will be no action.
Get Azm-Alt Z 12AB, 4000# 10 characters returned,
12AB=Azm, comma, 4000=Alt, #
Get RA-Dec E 34AB, 12CE# Scope must be aligned
Cancel Goto M #
Is Goto in Progress L 0# or 1# 0=No, 1=Yes; "0" is ASCII
character zero
Is Alignment Complete J 0# or 1# 0=No, 1=Yes
Commands below available
on version 1.6 or later
HC version V 1 6 # Version 1.6
Stop/Start Tracking Tx
x = 0 (Tracking off)
x = 1 (Alt-Az on)
x = 2 (EQ-N)
x = 3 (EQ-S) # Alt-Az tracking requires alignment
32-bit goto RA-Dec r34AB0500,12CE0500 #
32-bit get RA-Dec e 34AB0500,12CE0500# The last two characters will always
be zero.
32-bit goto Azm-Alt b34AB0500,12CE0500 #
32-bit get Azm-Alt z 34AB0500,12CE0500# The last two characters will always
be zero.
The cable required to interface to the telescope
has an RS-232 male plug at one end and a 4-4
telephone jack at the other end. The wiring is
as follows: