XML Config File

Most of the configuration is provided via a XML document. It is designed, to be very flexible in usage as well as easy to create.

Minimum Working Example

This example consists of OBD Service 01, with Parameter 004 and one channel.

<OBD-II version = "1.0">
   <Service id = "001" name = "Show current data">
      <Parameter id = "004" name = "Calculated engine load" frequency = "1">
         <Channel unit = "%">
            <NumericValue bit_length = "8" bit_offset = "0" type = "unsigned"/>
            <LinearScaling offset = "0" scale = "0.39215"/>
            <Range min = "0" max = "100"/>
         </Channel>
      </Parameter>
   </Service>
</OBD-II>

OBD 2 Service

An OXYGEN OBD 2 xml file describes one or more OBD 2 Services. Each Service has its own Service Id and name.

<Service id = "001" name = "Show current data">
   …
</Service>

<Service id = "005" name = "Oxygen sensor monitor">
   …
</Service>

Service Property	Value Options	Mandatory	Example	Description
name	string	yes	“My Endpoint”	Friendly name of the Service
id	number	yes	“1” until “/0xff”	Identification of the Service.

OBD 2 Parameter

Each OBD 2 Service includes one or more OBD 2 Parameters. Each Parameter has its a Parameter Id name and polling rate.

<Parameter id="004" name="Calculated engine load" frequency="1">
   ...
</Parameter>

<Parameter id="0xA6" name="Odometer">
   ...
</Parameter>

Parameter Property	Value Options	Mandatory	Example	Description
name	string	yes	“My Endpoint”	Friendly name of the Service
id	number	yes	“1”..”255”	Identification of the Service.
frequency	number	no	“0.01” until “10” Hz	Polling rate of the parameters channels

Channels

A Channel describe one return value of an OBD 2 Parameter request. Since one OBD 2 Parameter can return multiple values, one OBD 2 Parameter can include multiple channel sections.

<Parameter id="020" name="Oxygen Sensor 1" frequency="1">
   <Channel name="Voltage" unit="V">
      ...
   </Channel>

   <Channel name="Short term fuel trim" unit="%">
      ...
   </Channel>
</Parameter>

Channel Property	Value Options	Mandatory	Example	Description
name	string	no	“Coolant temperature”	Friendly name of a return value. For identifying OXYGEN data channels, the Parameter name and channel name are used if multiple channels are present.
unit	string	no	“km/h”	Unit of the underlying numeric value.

Numeric Value

The numeric value entry specifies position and type of the returned value. This is a mandatory entry of an OBD 2 channel.

<Channel name="Voltage" unit="V">
   <NumericValue bit_length="8" bit_offset="0" type="unsigned"/>
</Channel>

Property	Value Options	Mandatory	Example	Description
bit_length	number	yes	“8”, “16”	Size of the response value. This should be multiple of 8 (number of bits per byte).
bit_offset	number	yes	“0”, “8”, “16”	Offset of the response values first bit. Since OBD return values always start at the beginning of one byte, this should be 0, 8, 16, …
type	string	yes	“signed”, “unsigned”	Signed or unsigned number representation of the returned value. Signed specifies the two’s complement value representation.

Range

The range xml section describes the physical range of the underlying value and is mandatory.

<Channel name="Voltage" unit="V">
   <Range min="0" max="1.275"/>
</Channel>

Property	Value Options	Mandatory	Example	Description
min	number	yes	“-40.0”	Minimum value
max	number	yes	“215”	Unit of the channel’s underlying numeric value.

Linear Scaling

This is an optional xml tag for an OBD 2 Channel. The scaling parameters normally can be computed out of the OBD 2 Channel range entry. But sometimes the returned physical value range differs to the returned computer value range. For this the linear scaling tag specifies the real linear equation param-eters.

<Channel name="Voltage" unit="V">
   <LinearScaling offset="0" scale="0.39215"/>
</Channel>

Property	Value Options	Mandatory	Example	Description
offset	number	yes	“-40.0”	Offset of the linear equation
scale	number	yes	“0.39”	Factor of the linear equation