MotoHawk SAEJ1939 PGN Transmit DM19

This block sets up a DM19 PGN Transmit message using the specified handler.

Block ID

Library

MotoHawk_Protocols_lib

Description

The "PGN Definition" script is required to follow the template outlined in the "motohawk_saej1939_dm19tx_example" example file.

The definition script specifies a constant value, a port value, or an external datastore for each input parameter. The location of the block in the application will determine when the port-related information is updated.

This block will not transmit unless the PGN is requested via PGN 59904. DM19, being a PDU1 PGN, will always be sent to the requesting source address.

The definition script must add a link to the Calibration Verification Number (CVN) data as a SPN Scalar and the Calibration Identification (CALID) as a SPN Vector.

There can be multiple pairs of CVN and CALID but they must appear in pairs and must follow a few requirements:

For CVNs (SPN1634):
- The structure must be a "scalar".
- The data type of the SPN must be UNSIGNED.
- The bit length must be 32 bits.
- The byte order must be "LITTLE_ENDIAN".
- The starting bit must be 24.

For CALIDs (SPN1635):
- The structure must be a "vector".
- The data type of the SPN must be UNSIGNED.
- The length must be a constant 16 bytes.

These restrictions originate from the J1939-73 specification. If the above requirements are not satisfied, unpredictable results will occur when transferring the data.

The "Ready" port indicates whether the CVN has been calculated and is available for transmission. If the CVN is not ready, then the J1939 stack will respond with a NACK with reason 3 when DM19 is requested.

Block Parameters

Parameter Field	Values	Comments/Description
PGN Definition	String	Evaluates to a PGN Transmit DM19 definition specified in the example script.