Appendix D - RS-232 Connection

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

#

Alt-Az tracking requires alignment

 

x = 0 (Tracking off)

 

 

 

x = 1 (Alt-Az on)

 

 

 

x = 2 (EQ-N)

 

 

 

x = 3 (EQ-S)

 

 

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:

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Celestron 8i manual Appendix D RS-232 Connection, Communication Protocol

8i specifications

The Celestron 8i is a highly regarded telescope that has made a significant impact in the world of amateur astronomy, renowned for its performance, advanced features, and user-friendly design. Part of Celestron's Advanced Series, the 8i model boasts an impressive 8-inch Schmidt-Cassegrain optical system, which combines the advantages of a large aperture with a compact design. This allows enthusiasts to explore celestial objects with greater clarity, providing bright, sharp images of planets, star clusters, and nebulae.

One of the standout features of the Celestron 8i is its Fast Star capability, which allows for rapid imaging of celestial objects. Coupled with its advanced StarBright XLT coatings, this system enhances light transmission and increases contrast, resulting in a more vivid and detailed observation experience. This combination makes it an ideal choice for both novice and experienced astronomers who seek high-quality visuals of deep-sky objects.

The telescope's computer-controlled GoTo mount simplifies the process of locating and tracking celestial objects. With the push of a button, users can easily access a database containing over 40,000 astronomical objects, allowing for an effortless stargazing experience. The Celestron 8i also features an intuitive hand controller that enables users to customize their observations and seamlessly navigate the night sky.

The Celestron 8i is designed for portability, despite its robust optical performance. Weighing in at around 45 pounds, it is relatively easy to transport to different observing locations. The telescope's sturdy construction ensures stability while providing ease of setup, facilitating a hassle-free stargazing experience.

In terms of accessories, the 8i comes equipped with a 25mm eyepiece, offering a moderate magnification that is perfect for a variety of targets. Additionally, users can expand their observing capabilities with optional eyepieces, filters, and focal reducers, catering to both visual and astrophotography pursuits.

Overall, the Celestron 8i stands out as a versatile and powerful telescope that meets the needs of amateur astronomers at various skill levels. With its advanced features, superior optics, and impressive usability, the 8i offers a unique and rewarding experience under the night sky. Whether for planetary observation or deep-sky exploration, the Celestron 8i remains a top choice for astronomy enthusiasts.