GNSS Data Recording & Transmission Over CAN Bus.

In this example, we will see how to configure a ReXgen data logger to transmit the GNSS positioning data over the CAN Bus and record the GNSS data in the internal storage.

Following GNSS Data will be transmitted via CAN 0 Bus and recorded in internal memory:

Latitude Longitude Altitude Speed Over Ground Ground Distance Course Over Ground Number Of Satellites Quality

Documentation

The image below shows how each element is linked in the XML file.

image

They are connected using Unique IDs (UID).

Default Settings

• CAN Baud Rate: 500 Kbps

• GNSS Sampling Rate: 100ms

• CAN ID For various signals:

• 0x12B – Altitude, GPS Speed

• 0x12C – Longitude, Latitude

• 0x12D – Ground Distance

• 0x12E – Number Of Satellites, Course

• 0x12F - Quality

Example DBC provided with XML.

The following parameters can be modified by editing the XML as required.

Modifying CAN Bus Channel:

Edit the value of the PhysicalNumber element in the XML file under the CAN interface block. 0 for CAN 0, 1 for CAN 1, 2 for CAN 2 and 3 for CAN 3

<CANINTERFACE UID="2">
        <Type>CAN</Type>
        <PhysicalNumber>0</PhysicalNumber>
        <CANBusSpeed>500000</CANBusSpeed>
        <CANFDBusSpeed>8000000</CANFDBusSpeed>
        <CANFDNonISO>false</CANFDNonISO>

Modifying CAN Baud Rate:

Edit the value of the CANBusSpeed element in the XML file under the CAN interface block. Value has to be specified in bps

<CANINTERFACE UID="2">
        <Type>CAN</Type>
        <PhysicalNumber>0</PhysicalNumber>
        <CANBusSpeed>500000</CANBusSpeed>
        <CANFDBusSpeed>8000000</CANFDBusSpeed>
        <CANFDNonISO>false</CANFDNonISO>

Modifying GNSS Sampling Rate:

Edit the value of the SamplingRate element under the GNSSINTERFACE Block

Value has to be specified in milliseconds

<GNSSINTERFACE UID="3">
        <PhysicalNumber>0</PhysicalNumber>
        <SamplingRate>100</SamplingRate>
 </GNSSINTERFACE>

Modifying the CAN Identifier for the messages:

Edit the values of MessageIdentStart and MessageIdentEnd Elements under the CANMESSAGE block for the message you wish to edit. Please note that the example DBC will be invalid after this change.

Value has to be entered in Decimal

<CANMESSAGE_LIST>
      <CANMESSAGE UID="4">
        <MessageIdentStart>299</MessageIdentStart>
        <MessageIdentEnd>299</MessageIdentEnd>
        <Direction>OutputPeriodic</Direction>
        <DLC>8</DLC>
        <IsExtended>false</IsExtended>

Modifying the CAN Message transmission period:

Edit the values of Period Elements under the CANMESSAGE block for the message you wish to edit.

Value has to be entered in milliseconds

<CANMESSAGE_LIST>
      <CANMESSAGE UID="4">
        <MessageIdentStart>299</MessageIdentStart>
        <MessageIdentEnd>299</MessageIdentEnd>
        <Direction>OutputPeriodic</Direction>
        <DLC>8</DLC>
        <IsExtended>false</IsExtended>
        <InterfaceUID>4</InterfaceUID>
        <Period>100</Period>

Users can load the XML file into the ReXgen logger using the ReXdesk application/ReXdesk Convert application or the Rxlibrary DLL.

The process to send XML to logger using ReXdesk. Click on Config Menu > Run > Run Config Using External File > Browse the XML file and click Open.

GitHub Link

XML file

DBC file