Appendix D - Rs-232 Connection (For Computerized Hand Control); Communication Protocol - Celestron NexStar 8i Instruction Manual

A p p e n d i x D
A p p e n d i x D
H a n d C o n t
H a n d C o n t
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
Echo
Goto Azm-Alt
Goto Ra-Dec
Get Azm-Alt
Get RA-Dec
Cancel Goto
Is Goto in Progress
Is Alignment Complete
Commands below available
on version 1.6 or later
HC version
Stop/Start Tracking
32-bit goto RA-Dec
32-bit get RA-Dec
32-bit goto Azm-Alt
32-bit get Azm-Alt
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:
- R S - 2 3 2 C o
- R S - 2 3 2 C o
r o l )
r o l )
PC Command ASCII
Kx
B12AB, 4000
R34AB, 12CE
Z
E
M
L
J
V
Tx
x = 0 (Tracking off)
x = 1 (Alt-Az on)
x = 2 (EQ-N)
x = 3 (EQ-S)
r34AB0500,12CE0500
e
b34AB0500,12CE0500
z
n n e c t i o n ( f o r
n n e c t i o n ( f o r
Hand Control Response
X#
#
#
12AB, 4000#
34AB, 12CE#
#
0# or 1#
0# or 1#
1 6 #
#
#
34AB0500,12CE0500#
#
34AB0500,12CE0500#
65
C o m p u t e r i z e d
C o m p u t e r i z e d
Notes
Useful to check communication
10 characters sent. B=Command,
12AB=Azm, comma, 4000=Alt. If
command conflicts with slew limits,
there will be no action.
Scope must be aligned. If
command conflicts with slew limits,
there will be no action.
10 characters returned,
12AB=Azm, comma, 4000=Alt, #
Scope must be aligned
0=No, 1=Yes; "0" is ASCII
character zero
0=No, 1=Yes
Version 1.6
Alt-Az tracking requires alignment
The last two characters will always
be zero.
The last two characters will always
be zero.