Upgrade to the TCSGalil™ Telescope Control System

This control system and its predecessors are used on more professional telescopes than any other control system world wide. The DFM Engineering TCSGalil™ provides a new user-friendly interface to the telescope.  Over the past decade, DFM has put considerable effort into completely redesigning the telescope control system and rewriting core software to provide our third and ultimate generation of our telescope control system.  These control system retrofits incorporate the latest and best technology now available to revitalize the telescope with modern offerings, giving your telescope a longer service life.

Many DFM Engineering telescopes (and LIDAR scanners) are using computer control systems that are 30+ years old. Computer and encoder technology has rapidly advanced leaving many older components and operating systems unavailable and unsupported.  With the obsolescence of the ISA computer bus, it became necessary to look for a new approach to mount control that isn’t highly dependent on internal PC architecture. 

The feature set of the Third Generation brings new functionality. No longer do servo motor tune-ups for the telescope require an oscilloscope to adjust potentiometers. New software-controlled digital servo motor controllers allow tune-ups that can adjust for any servo imprecision on the telescope mount. Optional Renishaw 26-bit absolute position encoders working with the controller to enable absolute positioning. Now motor encoder reporting can be reconciled with that of the actual telescope mount positioning, closing the loop, to enable more precise, smoother, and accurate tracking of fast moving objects. This option also increases productivity and telescope availability by eliminating the sometimes nightly zero-point procedure of locating a star near zenith in order to determine zero-point positioning, a procedure that can be particularly difficult for higher F-ratio telescopes (see our PFI™ page on how to retrofit these dinosaurs to do modern science). Movement of the telescope, when the control system is powered off, no longer results in losing observation time running the zero-point procedure. Instead, with the Renishaw absolute encoders, the zero-point procedure will only be rarely required.

A Renishaw linear travel absolute position encoder can also be installed on the focus motion to replace the existing sliding potentiometer / incremental encoder system, eliminating time spent searching for the fiducial, allowing precise focus positions to be returned to easily, a particularly useful feature when varying pre-determined focus positions are required for multiple instrumentation (check out our new Multiple Instrument Adapter) or filters.

This Third Generation DFM control system consists of two rack-mountable chassis:  the computer chassis and the new Motor Driver Chassis (MDC). The computer chassis is a chassis mounted modern multi-core PC running the current version of the Windows operating system. The MDC is a custom DFM hardware unit that connects existing motors, motor encoders, position encoders, and cables with a Commercial Off-The-Shelf (COTS) multi axis Digital Motor Controller (DMC) from Galil Motion. 

To minimize disruption, this system is designed to be up and running in a few days utilizing your existing hardware, such as motors, encoders, and hand-paddles. The communication between the observatory PC and the new TCS control system has been simplified to a single Ethernet cable, allowing the user to upgrade or replace PC hardware without worrying about compatibility with the mount hardware. The new MDC also increases control system robustness by including sacrificial daughter boards to address the leading cause of failure of previous ISA-based systems - lightning-strikes.  This signal conditioning and surge protection hardware makes this unit well suited for observatory control room installations distant from the telescope.

On the software end, the TCS application has undergone a complete rewrite from the inside out. Starting with a well-defined philosophy for control logic and inter-system communication, the new TCSGO application was designed to handle frequent commands and queries from multiple sources, expanding the native command set, while maintaining high frequency control loops and a responsive user interface. All commands are available to your external computer, allowing you to create your own custom user interface where TCSGalil™ becomes a peripheral to your computer system, allowing integration with your own observing program.

Additional features available in the modern TCS include support for absolute on-axis encoders, closed-loop position control (with our unique Iterative Cubic Envelope Engine [ICEE]), and over 70 commands for unparalleled remote scripting and automation possibilities. The new TCS software supports traditional remote commands delivered through a serial port or a TCP/IP connection as well as local commands*2 delivered via the ASCOM standard (focus, dome, and telescope), introducing this feature-set to many older DFM telescopes. The end result is a unified code base that all customers share, handling all the features of multiple sites, in a single small executable.

Your existing control computer, ISA card and associated cable, and the existing motor driver chassis are no longer used, but the cables between the old motor driver chassis and the mount, the servo motors and motor encoders, and the positioning encoders, if not replaced by Renishaw absolute encoders, are used with little or no change, so all must be in operating condition. Repair or replacement of this hardware is not part of this contract unless explicitly listed as an option. The wear items (e.g., the timing belts) should be replaced at time of upgrade to assure optimal performance.

COSTS: within continental USA


  • TCSGO control system retrofit, including a modern PC, a new Motor Driver Chassis, and updated electrical drawing package.*1
  • One year of software upgrades, telephone and email support. Included
  • Shipping of installation hardware (freight FOB destination). Included


  • A remote station, consisting of a 27” display and a keyboard and mouse (via HDMI and USB extensions), allowing operation of the TCS computer from a remote location (up to 150’ away). This is typically used on the observing floor near the telescope. 
  • Mount conversion to Renishaw absolute on-axis encoders, providing sub-arc-second position resolution with no need for initialization, RA and DEC 
  • Focus conversion to Renishaw absolute linear travel encoder. This option requires return of the focus housing to DFM Engineering for installation. Ideally this is done after the retrofit to coincide with mirror servicing to minimize or eliminate additional down-time. 
  • Extended support, providing up to five years of software upgrades and support from a DFM technician. 


For a limited time, systems that are upgraded with the Renishaw absolute encoders on RA and DEC will receive a FREE Beta copy of the DFM Sat-Track Software, valued at $25,000. This software represents our new age of space utilization. With over a million satellites predicted to be circling the earth, your observatory will unlock opportunities for education in physics and astronomy, exciting students who will be able to observe orbiting satellites. DFM Sat-Track Software provides the propagation from the two line element set (TLE) used to describe the orbit of satellites, into mount angles and velocities so that DFM telescopes can track satellites at very high speeds compared to stellar motions.  Combined with the Third Generation TCS, the closed loop provides precise, smoother, and accurate tracking of orbiting objects, within the limitations of telescope acceleration and velocity capabilities.  In development for over 35 years on multiple sites around the world, this software is nearing official release.  This new ability reflects DFM Engineering’s inflection point from astronomy into space domain awareness systems and laser satellite communication terminals made possible by our new 26-inch F/1.7 Prime Focus 4.4-degree FOV LEO Scope™.

This FREE Sat-Track Software offer expires upon official release of this new software. 

Typical payment terms are 50% deposit at the time of order and balance due NET 30 days from invoice date. Typically delivery is within three months after receipt of down payment. This quotation is valid for 120 days from the date at the top of this letter. Rates are subject to change after 120 days, with typical increases of 5% every six months.

DFM Engineering, Inc. is an American small business as defined in the Federal Acquisition Regulations.

* 1 Customers with position encoders that include position pot encoders or Heidenhain encoders on RA and DEC are not supported as replacement parts are no longer available. These systems require the RA and DEC Renishaw encoder upgrade. Telescopes with 5-Axis focus housings also incur additional charges.  All standard TCS software features are included, however, customized TCS features for certain installations will require software porting, incurring additional charges.  

* 2 While 3rd party software may run on our TCS computer such as The SkyX, DFM offers no interoperability guarantees for other manufacturers’ software, as some imaging software compatibility issues are currently known to exist.

All control systems and documentation are supplied with a continuation of the original Non Disclosure, Non Manufacturing license agreement or equivalent restricted data rights Government Federal Acquisition Regulation (FAR) clause.

Other Upgrade Options
DFM Engineering also offers other upgrade options for customers. Older computers can be replaced with a new PC that supports their older hardware. In addition, Legacy DOS system can be upgraded to a Second Generation Windows based TCS (WinTCS) offering an improved user interface using the 32-bit windows XP Pro operating system with their existing I/O board combination.  The Second Generation TCS upgrade runs on a new industrial computer still being manufactured for support of legacy industrial control systems which include ISA slots, and comes with new, fully licensed installation of Windows XP Pro and WinTCS code. 

The move to Windows from DOS facilitated the easy addition of Ethernet for external computer control versus legacy RS-232 serial communications. The reason for continued use of Windows XP Pro for these upgrades is related to issues in current versions of Windows operating system lacking support for older ISA slot hardware. In the event of IT concerns over the use of this older operating system, DFM can recommend IT hardware and software solutions that provide a secure operating environment while using Windows XP as the control system for your telescope.

The Second Generation TCS uses the same servo motor controllers driven by the same DFM ISA circuit board as in the Legacy system with the ISA circuit board installed in a new industrial computer. The rest of the hardware including the Motor Driver Chassis (MDC), the cables, the servo motors, and the encoders are used with little or no change so all must be in operating condition or replaced. The wear items (e.g. the timing belts) can also be replaced. Renishaw absolute encoders are not supported by the second generation TCS upgrade as these encoders require a special interface. 

For those seeking to maintain the same functionality and user interface without operator retraining or other hardware expense, users can continue to use their DOS installation on a new PC.  

These control system upgrades comes with email and telephone support provided by DFM Engineering.

COSTS within continental USA:

  • New Computer:   Base Price  $ 5,500  Plus shipping and code migration by DFM, if required.
  • Legacy DOS to WinTCS Second Generation TCS upgrade:  Base Price  $45,000  Plus shipping