The EQMOD ASCOM Driver is a software module that allows direct control of Synta mounts such as EQG, EQ-6, EQ-5, Sirius, and upgraded older Atlas mounts sold by Orion USA or Skywatcher. It either requires a modification of the hand controller or a small module such as EQDIR from Shoestring Astronomy:
http://www.store.shoestringastronomy.com/index.htm
or a special adapter cable, such as the one available from Pierro Astro:
http://www.pierro-astro.com/
or
Xagyl Communications who have a USB and an RS232 version
to convert RS-232 (or USB) signals to TTL levels to communicate with the motor controller board in the mount directly (no hand controller will then be needed).

For those wishing to build their own interface, the details can be found here:
http://eq-mod.sourceforge.net/eqdirect.htm although a commercial interface module is recommended since the cost is quite small.

With the EQMOD ASCOM driver, the user will be able to control the EQ mount using any ASCOM compliant planetarium software at 0.144 arcsecond resolution. The driver supports almost all the ASCOM method and properties which include;

•  SYNC (via ASCOM / Planetarium Software)
•  GOTO/SLEW at 0.144 resolution (depending on the accuracy of the planetarium database)
•  PARK TO HOME/PARK TO CURRENT/UNPARK
•  1-point ALIGNMENT & N-point alignment
•  PULSEGUIDE (variable rates with 'duration' parameter support and duration override)
•  ST4 guiding

• SIDEREAL, LUNAR, SOLAR TRACKING
• AUTOGUIDER PORT SPEED RATE SETTING (RA and DEC speeds can be set independently)
• VARIABLE SLEW SPEEDS which can be set from x1 to x800 of the sidereal rate
• NORTH and SOUTH Hemisphere support
• EQMOD SLEWPAD - Use a three button mouse use as a SLEW HAND PADDLE.
• GAME CONTROLLER/JOYSTICK control of mount
• GPS SUPPORT (using NMEA streams)
• USER PROGRAMMABLE TRACKING RATES (both on DEC and RA)
• PEC TRAINING (via hand control or PULSEGUIDE sequence) AND PLAYBACK (ring counter position accurate)
• STORAGE/RECALL of alignment data

Note: This documentation sometimes refers to the “encoders” in the mount. Strictly speaking, the mount doesn't have optical encoders, instead, the mount uses 32bit ring counters to keep track of the stepper motor position. The more appropriate term to describe the stepper motor counters would be “RA position counter” or “DEC position counter” (or just “RA or DEC counter”) instead of “encoder”.