This PV485 configuration provides an example of how to implement reception of J1939 Multipack messages that contain ASCII characters in the data bytes.
PGN 65242 and 65259 are multipack messages that using BAM Transport Protocol can contain as many as 7 bytes per message * 255 messages = 1,785 bytes of ASCII data.
This example assumes the user knows how many bytes of data the ECM is sending for each data field in the PGN's,
The messages are setup in the J1939 library as any other J1939 PGN and the fast packet check box is selected to indicate it is a multipack message.
These parameters are then setup in the configuration tab under the engine device just as you would for oil pressure or any other engine parameter.
Script routines located in the "ASCII Parameters" and "System Info" folders put these variables into an array which can then be converted from ASCII to a string that is then displayed on a page.
By J1939 definition these PGN's are only sent by request. A state machine is used to periodically send the RQST message PGN 59904 only while on the System Info page.
A freeform CAN message is used for this. The desired requested PGN is alternated between 65242 and 65249.
To test this configuration a CANCapture workspace is provided that sends out the matching multipack messages. Two script blocks are used to broadcast each PGN. Only one can be active at a time so use the enable/disable block function to activate the desired one.
This example was created in Powervision 2.9.23044 for a PV485.
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