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Create and Use J1939 Parameter Groups

This example shows you how to use Vehicle Network Toolbox™ with J1939 to create and manage J1939 parameter groups using information stored in CAN database files. This example uses the CAN database file, J1939.dbc. Creating and using parameter groups this way is recommended when needing to transmit data to a J1939 network.

Open the Database File

Open the database file to access the definitions.

db = canDatabase('J1939.dbc')
db = 

  Database with properties:

             Name: 'J1939'
             Path: '/tmp/Bdoc21a_1606923_186772/tpa01cb52b/ex46196345/J1939.dbc'
            Nodes: {2x1 cell}
         NodeInfo: [2x1 struct]
         Messages: {2x1 cell}
      MessageInfo: [2x1 struct]
       Attributes: {3x1 cell}
    AttributeInfo: [3x1 struct]
         UserData: []

Create a Parameter Group

Use the j1939ParameterGroup function to create a parameter group using the information contained within the database.

pg = j1939ParameterGroup(db, 'VehicleDataSingle')
pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 6
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 254
    DestinationAddress: 254

   Data Details:
   -------------
             Timestamp: 0
                  Data: [255 255 255 255 255 255 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []

Set Source and Destination Addresses

To fully define the parameter group and determine the logistics of its transmission on a network, set the source and destination addresses.

pg.SourceAddress = 30
pg.DestinationAddress = 50
pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 6
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 254

   Data Details:
   -------------
             Timestamp: 0
                  Data: [255 255 255 255 255 255 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 6
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [255 255 255 255 255 255 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []

Set Priority

Set the Priority property to further customize the transmission.

pg.Priority = 5;

View Signal Information

Use the Signals property to see signal values for this parameter group. You can directly write to and read from these signals to pack or unpack data in the parameter group.

pg.Signals
ans = 

  struct with fields:

    VehicleSignal4: -1
    VehicleSignal3: -1
    VehicleSignal2: -1
    VehicleSignal1: -1

Change Signal Information

Write directly to a signal to change a value and read its current value back.

pg.Signals.VehicleSignal1 = 10
pg.Signals.VehicleSignal2 = 100
pg.Signals.VehicleSignal3 = 1000
pg.Signals.VehicleSignal4 = 10000
pg.Signals
pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 5
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [10 0 255 255 255 255 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 5
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [10 0 100 0 255 255 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 5
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [10 0 100 0 232 3 255 255]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 5
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [10 0 100 0 232 3 16 39]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


ans = 

  struct with fields:

    VehicleSignal4: 10000
    VehicleSignal3: 1000
    VehicleSignal2: 100
    VehicleSignal1: 10

Write New Direct Data

You can also write values directly into the Data property, although setting values through Signals is generally recommended and preferred.

pg.Data(1:2) = [50 0]
pg.Signals
pg = 

  ParameterGroup with properties:

   Protocol Data Unit Details:
   ---------------------------
                  Name: 'VehicleDataSingle'
                   PGN: 40192
              Priority: 5
         PDUFormatType: 'Peer-to-Peer (Type 1)'
         SourceAddress: 30
    DestinationAddress: 50

   Data Details:
   -------------
             Timestamp: 0
                  Data: [50 0 100 0 232 3 16 39]
               Signals: [1x1 struct]

   Other Information:
   ------------------
              UserData: []


ans = 

  struct with fields:

    VehicleSignal4: 10000
    VehicleSignal3: 1000
    VehicleSignal2: 100
    VehicleSignal1: 50