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FX
-J1939 User's Manual
3U
2. When receiving messages
The CAN-ID, status/control flags and data bytes of each message are as follows.
Note
In case more than one ID can pass the filter set in BFM #1100 to #1267, the received CAN-ID might change.
The CAN-ID, DLC and data of the latest received message will always be displayed.
1) CAN-ID
The 32 bit source CAN-ID of the received Layer 2 message is stored. Values are as follows:
- 11 bit mode: 0 to H000007FF
- 29 bit mode: 0 to H1FFFFFFF
Function Mode
Layer 2 communication
(11 bit ID) mode
Layer 2 communication
(29 bit ID) mode
*1.
The "n" corresponds to the Layer 2 message number.
2) Status/Control Flags
High Byte/Low Byte
High byte
Low byte
*2.
If bit 8 of the Status/Control Flags is ON, a new frame including new data has been received and
stored. If bit 9 is ON but bit 8 is OFF, the same message (same ID, DLC and data) has been
received. If bit 10 is ON, at least one more frame has been stored in this message buffer while bit 8
was ON which caused an overflow condition.
Status/Control
Flags
New data (bit 8)
New frame (bit 9)
Overflow (bit 10)
3) Data bytes
The data received of length specified by DLC is stored.
In case the received DLC is less than 8, unused data bytes are set to H00.
7.1 [BFM #100 to #399] Sending/Receiving Pre-defined Layer 2 Messages
For Layer 2 message configuration in BFM #1100 to #1267, refer to Section 7.2
CAN-ID is stored in the 11 bits, bit 0 to 10, in the CAN-ID n
In this function mode, CAN-ID n
CAN-ID is stored in the 29 bits, bit 0 to 28, in the CAN-ID n
*1
Handle CAN-ID n
LW and CAN-ID n
H00:
New data is not received.
Bit 8:
ON when new data is received.
Bit 9:
ON when new frame is received.
*2
Bit 10:
ON when overflowing.
Data length count (DLC) of the received CAN frame.
New frame
New frame
no new data
new data
OFF
ON
OFF
OFF
7 Layer 2 Communication Mode (11/29 bit ID)
For the function mode, refer to Section 5.4
Description
*1
LW.
*1
HW does not used.
*1
LW and CAN-ID n
*1
HW by 32 bit instructions.
Description
Receive messages only
New frame
New frame
no new data
overflow occur
overflow occur
ON
ON
ON
OFF
ON
*1
HW.
new data
No data received
ON
- (Do not care)
ON
OFF
ON
- (Do not care)
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