Not sure about the Innova 3100 and if it can do anything else besides read engine and transmission codes. This would make it limited and I would prefer if you purchased something a little more robust. Buy from here
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(which requires a computer or other device) will sell you the preferred adapter for VWs. It is an investment that you can sell when you need to sell it.
There are 'VW' clones you can buy off of ebay but they are limited as to what they can do. The newest VWs supposedly require CAN enabled scanners. For under $20 (ebay) you could try one of these out along with the ross-tech software to see if things work well. Or these 'VW' stand-alone ebay items #..........
380093185753
120354755588 (CAN)
200293332319
110331458950
It all depends on what you want to do though. If you are only reading codes then there are probably some cheaper code readers out there. Now here is just a 'VW' code reader 370138041799 ($28 shipped)
Those generic readers are also limited as to what they can do on the VWs. Read info here
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"1.10 What's the difference between VAG-COM and an OBD-II Scan-Tool? OBD-II is a government mandated diagnostic protocol that is primarily aimed at diagnosing emissions-related problems. An OBD-II scan tool will work in many different brands of cars. VAG-COM uses VW's proprietary diagnostic protocol and will only work in VW/Audi vehicles. Although you can use an OBD-II Scan Tool in an OBD-II compliant (1996 or newer) VW or Audi, an OBD-II Scan Tool can only talk to the engine, not the numerous other "intelligent" systems in the car. Want to reprogram your central locks or your Radio? Diagnose a problem with your ABS, Airbags, or Automatic Transmission? Re-align your Immobilizer after swapping ECU's? Reset your Service Reminder Indicators? Communicate with a pre-1996 model (not OBD-II compliant) car? An OBD-II Scan-Tool can't do any of these things."
If you have a laptop go with either the ross-tech adapter or a clone if you are not buying a very new VW. JMHO