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-J1939 User's Manual
3U
5. DLC (data length count)
Set the number of bytes to be transmitted to 0 to 8 bytes for standard messages (single frame).
For the last four settings (BFM #950 to #973), the DLC can be up to 250. Please keep in mind that the
transmission/reception of this amount of data must be segmented and transferred in multiple CAN messages
and should be used for non time critical data only (e.g. recipes, configuration or text to be displayed on a
HMI.).
Setting range: K0 to K8 [K9 to K250] (standard message 1 to 75), 0 to 250 (extended message 1 to 4)
Note
If the four extended buffers are not sufficient, several standard 8 byte message buffers can be combined to
transport messages of up to 250 bytes. If the DLC of a standard message is set to 9 bytes or more, many
subsequent messages are occupied to buffer the number of data bytes defined by the DLC. The subsequent
configuration BFMs are filled with copies of the parameters set in the first message If the DLC value occupies
more messages than available, an error will be generated for the DLC BFM (BFM #29 bit 6 ON, BFM #39 =
DLC BFM address).
e.g.
If the DLC of message 2 is set to 20 (3 standard 8 byte messages are required to transport 20 bytes), the
configuration set in message 2 (BFM #506 to #511) is copied into message 3 and 4 (BFM #512 to #523). The
message data is located in BFMs #104 to #113 for messages 2 to 4. BFMs #114 and #115 are unused.
Message 3 and 4 configuration BFMs (#512 to #523) are write protected and locked as long as the DLC in
message 2 remains 20. If message 2 DLC is set back to 8 byte or less, message 3 and 4 are released and
can be used independently from message 2 again. If the DLC is increased, further messages will be occupied
as required, as long as these messages are not already in use (PGN bit 0 to 17 parameter BFMs are not
equal to HFFFF).
It is not possible to combine extended messages with standard 8 byte messages or other extended
messages. The max. data block size is 250 bytes.
For a configuration setting example of a message larger than 8 bytes, refer to the following section.
For configuration setting example in J1939 communication mode, refer to Subsection 6.2.1
6. Filter PGN
Defines the PGN for receive messages. Receive messages are stored to the corresponding location in BFM
#100 to #399 (standard 8 byte messages) and BFM #1300 to #1799 (extended messages).
For valid PGN values, refer to the remote devices manual or SAE J1939 Specification
7. Filter Source Address
Can be used to define a stricter Filter. The PGN is received only if PGN and source Address filter are
satisfied. This can be required if a certain PGN/Information is transmitted by several nodes (e.g. PGN 65262
"Engine Temperature 1" received from two independent generator units).
Set the filter source address to H00FF to receive a PGN no matter which node is the source.
Setting range: K0 to K253, K255 (any source).
8. Receive Timeout [in units of 10 ms]
This setting can be used to define a timeout for the message reception. If the value is set to K0, the timeout
detection is disabled. If the value is set to a Value different from K0, the FX
of the user message. If no message is received for the defined time, an error (H2004) is set for the
corresponding user message slot.
Note
• If the Timeout time is set too short (e.g. 50 ms for a broadcast message which takes at least 100 ms) an
error is generated for this parameter.
• The timer is started when the module is set to online. If the message is not received at all, the reception
timeout error is generated "reception timeout"
• Values larger than K32767 will be displayed as negative values by the monitor software.
6.2 [BFM #500 to #973] Configuration Area
For Message specific error codes list, refer to Section 5.19
10 ms after the module is set to online.
6 J1939 Communication Mode
-J1939 is guarding the reception
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