diff options
| -rw-r--r-- | README.md | 75 |
1 files changed, 75 insertions, 0 deletions
@@ -42,6 +42,81 @@ is sent as a JSON object, separated by newlines. The format of each object is: a hexidecimal number in a string. Many JSON parser cannot handle 64-bit integers, which is why we are not using a numerical data type. +## Diagnostic Messages + +### Requests + + {"bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "payload": "0x1234", + "frequency": 0} + +**bus** - the numerical identifier of the CAN bus where this request should be + sent, most likely 1 or 2 (for a vehicle interface with 2 CAN controllers). + +**id** - the CAN arbitration ID for the request. + +**mode** - the OBD-II mode of the request - 0x1 through 0xf (0x1 through 0xa + are the standardized modes). + +**pid** - (optional) the PID for the request, if applicable. + +**payload** - (optional) up to 7 bytes of data for the request's payload + represented as a hexidecimal number in a string. Many JSON parser cannot + handle 64-bit integers, which is why we are not using a numerical data type. + +**frequency** - (optional, defaults to 0) The frequency in Hz to send this + request. To send a single request, set this to 0 or leave it out. + +TODO it'd be nice to have the OBD-II PIDs built in, with the proper conversion +functions - that may need a different output format + +If you're just requesting a PID, you can use a simplified format for the +request: + + {"bus": 1, "id": 1234, "mode": 1, "pid": 5} + +### Responses + + {"bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "success": true, + "negative_response_code": 17, + "payload": "0x1234"} + +**bus** - the numerical identifier of the CAN bus where this response was + received. + +**id** - the CAN arbitration ID for this response. + +**mode** - the OBD-II mode of the original diagnostic request. + +**pid** - (optional) the PID for the request, if applicable. + +**success** - true if the response received was a positive response. If this + field is false, the remote node returned an error and the + `negative_response_code` field should be populated. + +**negative_response_code** - (optional) If requsted node returned an error, + `success` will be `false` and this field will contain the negative response + code (NRC). + +**payload** - (optional) up to 7 bytes of data returned in the response, + represented as a hexidecimal number in a string. Many JSON parser cannot + handle 64-bit integers, which is why we are not using a numerical data type. + +The response to a simple PID requset would look like this: + + {"bus": 1, "id": 1234, "mode": 1, "pid": 5, "payload": "0x2"} + +TODO again, it'd be nice to have the OBD-II PIDs built in, with the proper +conversion functions so the response here included the actual transformed value +of the pid and a human readable name + ## Trace File Format An OpenXC vehicle trace file is a plaintext file that contains JSON objects, |