ASCOM and the Astro-Physics ASCOM V2 Driver

This web page describes the ASCOM driver for Astro-Physics telescope mounts.

Quick Start - For Experienced ASCOM Users::

Follow these steps to Install the Astro-Physics ASCOM V2 Driver

  1. Go to the ASCOM website and determine the required updates to Windows and DotNet for the latest ASCOM Platform Updates.Handbox
  2. Update your Windows OS and DotNet as recommended on the ASCOM site.
  3. Return to the ASCOM site and update your platform to the latest version including all platform updates.
  4. Once the ASCOM Platform is fully updated, review and possibly download the documentation and instructional videos if needed using the Quick Links section below.
  5. Install the latest ASCOM V2 Driver in the Quick Links table.
  6. Run the setup screen either directly through the installer or through Start => Programs => Astro-Physics => ASCOM Driver
  7. In the ASCOM Telescope Chooser of your ASCOM client program, select "Astro-Physics GTO V2 Mount"

The ASCOM Platform and the Astro-Physics ASCOM V2 Driver will provide you with more comprehensive and fail safe control of your Astro-Physics GTO mount. We encourage you to use this interface for PC-based control of your mount!

Quick Links:

  Date Link

Latest Released Version: 5.10.00

(recommended for all A-P GTO Mounts: supports GTOCP1, GTOCP2, GTOCP3, and GTOCP4 control boxes on the serial and COM ports).


NOTE: This version (or later) is required for the latest version of APCC.

IMPORTANT: if you are upgrading from version v5.08.01 or earlier you must uninstall the earlier driver first from Control Panel.

IMPORTANT: if you later downgrade from v5.08.03 or later driver you MUST uninstall the newer driver first from Control Panel.

July 12, 2017

History of Changes

AstroPhysics V2 Setup v5.10.00

IMPORTANT: if you are upgrading from version v5.08.01 or earlier you must uninstall the earlier driver first from Control Panel. This is required because the location of the driver and supporting applications has changed so as not to potentially interfere with other ASCOM drivers.

Latest Beta Version: (none)
Online Web Help July 12, 2017 AstroPhysics V2 ASCOM Driver Documentation (v5.10.xx)

ASCOM Conformance validation file:

July 12, 2017 AstroPhysicsV2.Telescope.Validation.txt (For v5.10.00)
PDF Documentation July 12, 2017 AstroPhysics V2 ASCOM Driver PDF (v5.10.xx)
Amazon Kindle format (.mobi) July 12, 2017 APV2_Driver_5.10.mobi
Apple ePub format July 12, 2017 APV2_Driver_5.10.epub
Video Tutorials at Screencast.com June 2010 Video Tutorials at Screencast.com

Park 4

Park 4 has been added to APCC and the latest version of the driver. Park 4 parks the scope on the opposite side of the pier facing south to the horizon.

This was done to overcome a potential Park 1 issue. The issue would occur if the mount is allowed to track into a counterweight up position (i.e., telescope lower than counterweights) before initializing from the Park 1 position. Because the mount tracks west when powered there is only a minute or two before it will move into that counterweight up position, so it is critical to promptly initialize the mount.

The need to promptly initialize is because a "Sync" command is sent which always assumes the mount is in a counterweight-down position. If the mount has tracked into the counterweight-up position when the Sync occurs the mount controller will think the RA Axis is 180 degrees off from the current position so the mount will appear to be lost and dive under the mount when commanded to go to any sky target. It is not actually lost, it was just incorrectly initialized.

Note that while you can still use Park 1, do so at your own risk. We think that Park 4 instead of Park 1 is a superior solution. Park 4 has the advantages of Park 1 (e.g. scope is level) but none of the disadvantages.

Here is a comparison of Park 1 to Park 4 for the Northern hemisphere:

Park 1 vs Park 4

For Those Requiring (or wanting) a Bit More Information about ASCOM:

NOTE: Links to third party sites were current at the time of webpage publication, but are not under the control of Astro-Physics.

ASCOM Logo ASCOM Standards for Astronomy - The ASCOM Initiative

What is ASCOM?

ASCOM (AStronomy Common Object Model) is a go-between to allow different software packages to talk to different pieces of astronomical equipment. The ASCOM platform provides a common language for all the software, and then each individual driver translates that common language into the specific command laguage needed to make the equipment do what we want it to do.

The ASCOM initiative began in 1999 as new mounts and CCD cameras, each with their own unique control systems came on the market. Bob Denny of DC3-Dreams and others realized the complexity of developing mount and camera control software that could be used with a wide variety of instruments. The task of software developers to keep up with new mounts, cameras, focusers, etc. as they came on the market, or to stay abreast of revisions to the code of existing equipment was an enormous (or more correctly: insurmountable) task. So, the ASCOM Initiative was born to establish, develop and promote a driver-client architecture just as the computer industry had done earlier with printers, cameras and other peripherals. For even more information, check the following link: About ASCOM.

Why should I use ASCOM and the Astro-Physics ASCOM V2 Driver?
The ASCOM platform and the ASCOM V2 AP driver are not required to run PulseGuide, and they are certainly not required for control of the mount with the Astro-Physics GTO Keypad. However, the platform and driver are required for PEMPro, ACP (by DC3 Dreams), and other programs, and are extremely useful for anyone wishing to control their mount from an external Windows computer. Most advanced planetarium and telescope control software packages have an option to use the ASCOM platform, or else they require it outright. (Note that these options are referred to as "telescope" control, but the telescope is just along for the ride. It is the mount that is being controlled.) We recommend that you select the ASCOM interface if it is an option in your software. The ASCOM option will be called the Telescope API (Application Programming Interface) This API will then allow you to use the Astro-Physics V2 Driver. The ASCOM Platform and the AP V2 driver will provide you with more comprehensive and fail-safe control of your mount.

The Astro-Physics V2 driver has been developed specifically for Astro-Physics by Ray Gralak. Unlike the earlier driver, this V2 driver is now fully owned and supported by Astro-Physics. It has been through rigorous testing and is being treated as an on-going project. We thank Ajai Sehgal for the first driver, which he developed on his own. It was a monumental effort that has served our customers well for many years. The new V2 driver, however, is much more fully developed and takes advantage of the advances to the ASCOM platform. If you are currently using the old driver, we strongly suggest that you upgrade. Check out the Features of the Astro-Physics V2 Driver that differrentiate it from the earlier driver.

We also advise you to keep your ASCOM updated to the latest version. At the publication of this webpage, ASCOM is in platform 6. This is a major upgrade from Platform 4.x. For a complete listing of the revisions to the standard, go to the ASCOM History Page.

Installing and Updating the ASCOM Platform, Astro-Physics V2 Driver and other Components
In order to use the Astro-Physics V2 driver, you will need to install these components which are discussed in further detail below:

  1. Current updates and Service Packs for your Windows Operating System
  2. Microsoft DotNet Framework
  3. ASCOM Platform - Current Release and Updates
  4. Astro-Physics V2 Driver

Microsoft Windows OS and the Microsoft DotNet Framework:
The current release of the ASCOM platform is designed to work with the Microsoft DotNet Framework. It is important that you keep your computer current with the latest updates to the Operating System (i.e. Service Packs) and to the DotNet Framework. The ASCOM website has been pretty good about providing guidance here. As you install the ASCOM platform, you will be instructed which version of the Dot Net Framework is required, either in a warning dialog box as you attempt to install the software, or through instructions on the ASCOM download page. See the section below on the DotNet Framework for more detailed information. Please perform all System and DotNet upgrades BEFORE installing the ASCOM components!

Installing or updating the ASCOM Platform.
If you are installing the platform for the first time, the installation is rather straight-forward once the necessary Windows and DotNet updates have beeen completed. If you are updating from an earlier platform version, pay special attention to any warnings or instructions that you see on the web page or in the installer program. Some platform updates may require that you first uninstall a previous version. The installer program will guide you. At an earlier date, it was recommended on the ASCOM site that you NOT uninstall earlier versions, but that recommendation has now been removed, and is apparently no longer valid. The only valid instruction that we can provide is to follow all instructions on the ASCOM website to the letter! To install, click the link below and click the download button on the respective web page. Also be sure to install the AP V2 driver after the full platform installation is finished as described in the instructions a bit further down.

PLEASE NOTE: Since it is important to use the latest versions of the platform, we provide the necessary links to the various web pages where the most current files can be found. Please add these pages to your favorites (bookmarks) and check regularly for updates!

ASCOM Platform 6.x.
Simply click the link above to go to the ASCOM website's home page. On the right hand side of the page is a Platform 6 Download Box. You should also install Platform 6, Service Pack 1. Click the download button and follow the installer instructions to install the platform from the website. In a normal installation, you should then be instructed to proceed to the most recent update release of the platform. Be aware that the latest platform update may also require the latest DotNet upgrade. This is why we advise keeping your Windows Operating System and DotNet Framework updated. Handbox Expanded

AstroPhysics V2 Driver
This is a completely new driver conforming to the ASCOM V2 Standard. To use this driver, the ASCOM Platform 5.x or later must be installed (Platform 6 is recommended). It will not work with earlier platforms. The AP V2 driver page can also be accessed through the ASCOM website.

To install the driver, simply click the link in the QuickLinks table under the "Latest Version" heading and either run the file or save it and run it later. You do not need to uninstall a previously version version of the driver, even if you want to install an older version over the top of a newer version.

This page will always have the latest help documentation for the driver. Since the driver and the documentation are both ongoing works in progress, we suggest that you also bookmark this page and check back often for the latest versions.

Instructional Videos for the AP V2 ASCOM Driver - MPEG 4 movie files:
Installing the AP V2 Driver
Setting up your AP V2 Driver
Operating your Mount with the AP V2 Driver

Features of the Astro-Physics V2 ASCOM driver as compared to the v4.1.xx driver:

Some Special Notes on using The Sky from Software Bisque
To use the ASCOM interface from The Sky planetarium software, you will need to install a plug-in. Instructions for this are on the ASCOM website at this link in the FAQ pages. Scroll down to the section entitled: 2. TheSky Controlling a Telescope With an ASCOM Driver.

Old ASCOM
Since the ASCOM v. 5.0 and later Platforms are not compatible with older computers with operating systems that predate Windows XP, we have also included links to the previous platform version and AP driver below. If you have a computer running Windows XP or later, we DO NOT recommend using the old platform and driver!

ASCOM Platform 4.1
Original ASCOM AP Driver