I had occasion to pick up a pair of GridConnect CAN RS232 adapters at a cheap price a couple of months ago, while trying to interface some pieces to a CAN BUS system. These adapters are designed to connect between a DB-9 connector (a common 9 pin serial port) and a CAN BUS system. These are the older adapters, the newer ones connect the CAN BUS to USB connector. Many older devices and laptops have a serial port with a DB-9 connector, or a simple USB-DB-9 connector is easily found and quite cheap.
Today, I found two more on EBay at
http://www.ebay.com/itm/Canbus-Adapter-/332145244286?hash=item4d5566387e:g:fjgAAOSwXeJYJ5sp and there are two in the box, along with two regulated 500 milliamp power supplies, and the complete CD of manuals, currently priced at a Buy-It-Now $16.96 including shipping for two. These sell for $240 for the pair.
http://gridconnect.com/rs232-can-converter.html In addition, the company is local, and extremely helpful, even though these units are older stock. These units are new, in the original box.
This will allow you to interface your laptop (or smartphone with a USB OTG adapter) to the CANBUS in any EV made since 1996. You can send and receive commands from your laptop through one of these adapters quite easily. But even niftier, is to add onto your CAN BUS system by connecting two of these adapters. In order to make many these things work, you need two CAN bus connections, one to send a signal, and one to receive signals. This is two adapters in the box along with all the manuals on CD ROM for under $17.
If you plan to connect directly to the CAN BUS system, you will need to connect the two terminals on the adapter to the twisted wire pair for the CAN BUS network in the vehicle. That twisted wire pair is easy to find, and carries CAN-High and CAN-Low signals. If you plan to interface with the OBDII port under your dashboard, you will need to get a cable to interface with that port. Warning, there are two cables that have a OBDII male end and a DB-9 connector, one is an interface cable and one is an adapter cable. For the Grid Connect adapters, you need the Interface cable; I found one at Mouser
http://www.mouser.com/search/ProductDetail.aspx?r=734-OBD-M-DB9-F-ES If you plant to use an arduino or a raspberry pi, you likely will use the SparkFun board at
https://www.sparkfun.com/products/9555 Spark Fun sells a cable that works with their board. What is the difference?
| | | Adapter Cable - Sparkfun | Interface cable - GridConnect |
| OBD II | | 16 Pin : DB9 | 16 Pin : DB9 |
| Battery Power | | 16 : 9 | 16 : 6 |
| Chassis Ground | | 4 : 1+2 | 4 : 3 |
| Signal Ground | | 5 : 1+2 | 5 : 3 |
| CAN High J-2284 | | 6 : 3 | 6 : 2 |
| CAN Low J-2284 | | 14 : 5 | 14 : 7 |
| ISO 9141-2 K Line | | 7 : 4 | 7 : 1 |
| ISO 9141-2 L Line | | 15 : 8 | 15 : 8 (same) |
| J2850 BUS- | | 10 : 6 | 10 : 9 |
| J2850 BUS+ | | 2 : 7 | 2 : 5 |
| | | ? | 9 : 4 |
| | | Jayco Systems | Mouser |
As you can see, the CAN HI, which is on Pin 6 of the OBD II connector is on Pin 3 of the DB-9 from SparkFun and Pin 2 of the DB-9 from Mouser (GridConnect compatible)
CAN LO which is on Pin 14 of the OBD II connector is on Pin 5 of the DB-9 from SparkFun, and Pin 7 of the DB-9 from Mouser.
So, If you are going to use the OBDII connector under the dash as a connection point, get the correct cable and you will be fine with either the Grid Connect or the Spark Fun system.
