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Diagnostic Software for VW-Audi Group Cars

881 Sumneytown Pike, Lansdale PA 19446, USA

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            Product Information

Communications Interfaces

Ross-Tech can supply several different Interfaces (the hardware needed to connect a PC to your car).   One end of the interface plugs into the a Serial (RS232) or USB port on your PC.   See our  Computer Requirements.     The other end plugs directly into the OBD-II port present in all 1996 and newer VW/Audi passenger vehicles.   VCDS also works with many 1990-1995 (OBD-I) cars, but these may require the optional "2x2"cabling adapter.

All of our Interfaces offer the following advantages over others on the market:

  • Act as a dongle for the full-function version of VCDS.  No "Software Activation" required!

  • Precision-molded diagnostic connector made to our own specifications that fits all VW/Audi vehicles, even those with "tight" trim around diagnostic socket.

  • Work with "Lame Port" Laptops including Compaq and Acer models.

  • Built-in, Electronic Protection from the "Aftermarket Radio Problem".

  • Fully automatic support for 2002+ Audi models with dual K-lines without kludgy switches (KEY- and HEX-series).

How to choose the interface that's right for you:

First, decide how you're going to use VCDS:

  • If you're a professional mechanic who needs compatibility with all diagnostic-capable models from 1990 through the latest vehicles, or you're an enthusiast who demands the best, get a HEX+CAN. These Interfaces are also available in a Pro-Kit. See our Pro-Kit Page.

  • If you're a budget-conscious hobby-user just working on your own car, our KEY-series or Micro-CAN interfaces may be for you.  The KEY-series is compatible with most cars from 1990-2002, as well as all newer ones which do not require CAN for diagnostics.   The Micro-CAN is designed exclusively for use with the latest cars based on Mk.5 technology which require CAN for diagnostics.   However, the Micro-CAN is not compatible with the latest Audi A4, A6, A8, or Q7 models; these models require a HEX+CAN.

  • Check the Application Chart for your vehicle to see which Interfaces can be used with it.

Second, consider the PC you're planning to use:

  • If you're using a modern laptop running Windows XP, you should get a USB interface.   Although USB interfaces are no faster than the serial versions, it is becoming increasingly difficult to find new PCs with serial ports and a USB interface is more future-proof.

  • If your PC has a CPU speed of less than 1 GHz or is running an older version of Windows, we recommend using a serial interface -- but please check that your PC has a serial port with 9 male pins.

The following Comparison Chart may also help:  

  Enthusiast Interfaces
K-line or CAN (but not both).  Work great with the
cars they are compatible with, but not as fast,
or as compatible with "difficult" control modules
as our Professional-Grade Interfaces
Professional Interfaces
Universal K-line plus CAN.  
Instant Connection Speed,
 Fastest Sample Rates,
Greatest Compatibility
with "Difficult" Control Modules
Also available in a Pro-Kit
  KII-USB Micro-CAN HEX+CAN Series
Recommended for Professional Use No No YES
Supports latest cars which require a direct CAN connection No YES
 Cars based on Mk.5
technology only
Compatible with older cars that don't use CAN YES No YES
Enhanced protocol timing, compatible with 1991-1994 Audi 1Z TDIs and 1993-1994 2.6L V6. YES N/A YES
(when used with Windows XP)
Field Upgradeable Firmware in Interface No YES YES
"Turbo" Mode for Measuring Blocks on newer KWP-2000 ECU's No No YES
Use with dual K-Line  (2002+ Audi A4, A6 models) YES No YES
Acts as a "dongle" for VCDS,
No "Software Activation"
Protection from the "Aftermarket Radio Problem" YES, Electronic YES, Electronic YES, Electronic
Status/Activity LED YES, Red/Green YES, Red/Green YES, Red/Green
Price including
USB Only: $249 USB Only: $249 Serial or USB: $349


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Each Interface is more fully described on a page of its own.  Click on the pictures in the chart above to go to the respective page.

If you still don't know  which one is best for you, tell us what kind of car(s) you'll be working on, and what Brand And Model of PC you'll be using, contact us and we'll recommend one for you.

Audis that require Dual K-Lines:  

  • All  B6/8E chassis A4/S4 models with Xenon headlights.

  • All 2002 and newer A6 (C5-platform, 4B-chassis) models, including the Allroad.   

"Difficult" older cars

Include those with 1991-1994 Audi TDI engines which run the diagnostic protocols at 240 (yes, two hundred forty) bits per second,  1993-1994 Audi 2.6L engines with Hella ECU's, as well as any older car that has the "Check Engine" light connected to the L-Line (check wiring diagrams -- we don't have an exact list). 

"Lame Port" laptops

Include many Compaq Presario Laptops, some Acer models, and some ultra-portable Dell models which have the serial port on a separate port expander. All of our current Interfaces (shown above) work fine with these PC's.    Our older ISO-COM (no longer in production) and many third-party interfaces based on opto-couplers do not work with these PC's.

"Tight diagnostic sockets" 

Some models have very tight trim around the diagnostic sockets.  The gap between the trim and the socket itself is so small it is in violation of the SAE J1962 specifications.   All of our current Interfaces (shown above) fit fine in these these vehicles.  Some of our older interfaces as well as many third party interfaces use OBD-II connectors that do not fit these vehicles well. 
US Models:  1996 Audi A4.  1996 and 1997 Audi A6 Sedan, all 1996 and newer C4/4A Chassis Audi A6 (includes 1996 and 1997 Audi A6 Sedan and 1996 - 1998 Audi A6 Avant).
European Models:  All B5/8D Chassis  Audi A4/S4/RS4.   All 1997-2001 B5/3B VW Passat (before facelift).   All 1996 and newer C4/4A Chassis Audi A6/S6/RS6.  

Example of a car with tight trim around the diagnostic connector.
This is a 1999 European model Passat.

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