RotorDRV TSR to Yaesu GS-232 Adapter

Must Be Art > Software > KCTGS232


KCTGS232 is a DOS TSR (terminate-and-stay-resident) program for use with applications that use the antenna rotator driver interface defined by the Kansas City Tracker (KCT) and a Yaesu GS-232A external antenna controller, or any other controller that accepts the same command protocol.

The KCT software interface allows application programs, especially satellite tracking programs such as InstantTrack, to control a two-axis antenna rotator without needing to know any details of the hardware. The hardware driver, referred to as RotorDRV, is installed as a TSR program, and accepts commands through software interrupts. KCTGS232 fills this role.

The Yaesu GS-232 is an external smart controller, interfacing with the Yaesu meters-and-switches control box on one side and an asynchronous serial ("RS-232") port of a computer on the other side. The computer is responsible for keeping track of time and for computing the location of the target (usually a spacecraft in orbit). The computer sends azimuth and elevation angles to the GS-232, and the controller takes care of moving the antennas so as to point in the specified direction.

This program is a sort of adapter between the two types of interface. It looks like a KCT driver to the application program, and sends formatted commands out the serial port to the GS-232.

The package actually consists of two programs. KCTGS232.COM is the TSR driver itself. EC2START.EXE is a command-line application program that configures the TSR driver (tells it which COM port to use) and can enable or disable the TSR driver. (EC2START.EXE is identical to the one supplied with KCT-EC2, a similar program that implements a different serial port protocol.)

System Requirements

To run KCTGS232, an environment capable of running an MS-DOS TSR program is required. This certainly includes all versions of MS-DOS beyond 2.0. This program will also work under Windows 3.1, 95, and 98, but probably will not work under Windows NT, 2000, or XP.

The serial port used with KCTGS232 must be a 16550A-compatible UART, or equivalent, with 16-byte or larger FIFO. This is true of all modern PC serial ports (except USB serial ports), but older ports or highly-specialized multiport boards may not be compatible.



Current Status

Initial alpha test, version 0.03 released November 25, 2003. Works on my computer, and tested by G6LVB on the LVB Tracker and K1DM on a real GS-232A. No other test results yet.


Created by modifying KCT-EC2 in November 2003.

Known Bugs



KCTGS232 alpha test versions maybe distributed freely and may be used freely for non-commercial purposes only.

Source Code

Source code in assembly language for Microsoft MASM 5.1 (for the TSR driver) and Microsoft C 6.00A (for the control application), with a Microsoft NMAKE makefile that builds both, will be distributed freely after some additional alpha testing confirms the viability of this design approach.


KCTGS232.TXT - user manual (plain text, 5K)

DRVSVC.TXT - programmer's specification for the KCT software interface

INTSPEC.TXT - programmer's specification for the interfaces used by InstantTrack OrbitDRV


KCTGS232 0.03 (zip file, 12K)

Copyright 2003 Paul Williamson. Comments to kb5mu@amsat.org