Meade LX200 CLASSIC User Manual download pdf

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SOFTWARE AND HARDWARE AUTOGUIDING ISSUES WITH THE LX200GPS

If you’ve had problems getting K3CCDTools, GuideDog or other autoguiding software to successfully

control your LX200GPS through the RS-232 port, it may not be your mistake or faulty software that is

causing the problem. This paper explores a number of issues related to autoguiding through the RS-

232 port, and suggests solutions.

David Suder

November 2004

Introduction

Many LX200GPS owners have been frustrated in

their attempts to perform remote guiding of their

telescopes using serial commands directed to the

mount through the RS-232 port. This paper

examines some of the issues potentially causing

this frustration, and presents some solutions to

these problems.

Information presented here has been developed by

testing my 10" LX200GPS with several of the

most widely-used freeware packages, with serial

port monitoring programs, and with some

diagnostic programs I wrote with Visual Basic. I

also learned a great deal from information posted

on the ASCOM-Talk, Meade LX200GPS, Meade

LX200, Meade Uncensored and QCUIAG Yahoo

discussion groups, as well as

www.MeadeLX200GPS.com, the Meade

Advanced Products Users’ Group

(www.mapug.com), the Meade Instruments web

page, a number of other LX200GPS users, and

authors of some popular autoguiding software.

This paper should be considered a work in

progress. Meade continues to release new versions

of firmware for the LX200GPS, and software

creators continue to develop new drivers and

applications - all of which may affect the

information presented here.

This paper does not address guiding through the

LX200GPS autoguider port. Guiding in this

manner is an entirely different matter, generally

using hardware specifically designed for the task

(e.g., purpose-built CCD autoguiders). The

autoguider port of LX200 and other telescopes

and mounts expects, rather than serial

communications, contact closures to command

guiding movements. While not exactly “plug and

play,” there are a number of readily available

(although expensive) and relatively problem-free

solutions for autoguiding through the autoguider

port. Many LX200 users have reported good

success with these solutions.

External Control of the LX200GPS via

the RS-232 Connection

Meade computer-controlled telescopes (such as

the LX200, LX90 and ETX models) can be

commanded remotely by serial commands

delivered to the telescope through the RS-232

port. (See Figure 1.) A connection between the

LX200GPS and the serial port of a personal

computer (or other device such as a PDA) can be

made using Meade’s #507 connection cable. The

connection cable, which has a RJ-11 (telephone)

connector at one end and a female DB-9

connector at the other, can be easily put together

in a few minutes using the instructions posted at

http://www.meadelx200gps.com/images/other/L

X200_cable_diagram.gif and elsewhere.

Meade Telescope Serial Command Protocol

(MTSCP) is a series of commands, sent to the

telescope from a personal computer or other

device, that duplicate many of the capabilities of

the Autostar II handbox. Meade has published a

listing of the serial command protocol at

http://www.meade.com/support/CommandSet.h

tml. These commands can be generated by

software run on the personal computer or other

device. Not all of the commands available on the

Autostar II handbox are included in the MTSCP;

however, some commands are available through

the MTSCP that are not available via the handbox.

Most commands simply cause the LX200GPS to

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Summary of Contents

Page 1 - November 2004

-1-SOFTWARE AND HARDWARE AUTOGUIDING ISSUES WITH THE LX200GPSIf you’ve had problems getting K3CCDTools, GuideDog or other autoguiding software to succ

Page 2

-2-Figure 1. Use of the RS-232 portdo something, but some return information (e.g.,current pointing position or OTA temperature) tothe external devic

Page 3

-3-problem for imaging. Not only does the pausemove the target off center (blurring the image), itmakes it extremely difficult to accurately return t

Page 4

-4-y-directions2) from desired position3. Calculate the duration of slews (x- and y-directions) required at the current slew(guiding) rate to return t

Page 5 - Andrew’s program

-5-Apparently, Meade has added the command:Mgdnnnn# to the MTSCP and didn’t tell anyoneabout it. This command instructs the telescope tomove in direc

Page 6

-6-to the telescope. This allows programmers whofind errors in the ASCOM driver for a particulartelescope to send the proper commands throughASCOM.

Page 7

-7-alignment.ConclusionsSix months ago, successful autoguiding of theLX200GPS via the RS-232 port was essentiallyimpossible, having been thwarted by a

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