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6 J1939 Communication Mode
6.2 [BFM #500 to #973] Configuration Area
53
FX
3U
-J1939 User's Manual
1
Introduc
tion
2
Specifi
cations
3
Inst
allati
on
4
Wi
rin
g
5
Al
lo
ca
tion of
Buf
fer
Memor
ies
6
J1939 C
omms
Mode
7
La
ye
r 2
C
omm
uni
cation
M
ode
8
PL
C RUN>
S
TOP
Me
ssag
es
9
Co
mmand
Interface
10
Comm
uni
cation
Setti
ngs
Proc
edure
3. ttype (transmission type)
The transmission type defines the trigger for messages to be sent on the network.
All configured transmit messages will be sent when the module is set from configuration to online mode. After
this first transmission, the message will be sent every time the condition of the selected transmission type is
satisfied.
The following table describes the relation between ttype and communication method (transmission of data).
*2.
J1939 communication mode does not use remote transmit request (RTR) frames to request certain
information from the network.
The CAN Layer 2 function RTR will not work because although the priority and the source and the
destination node address are part of the J1939 CAN-ID, they might not be known by the requesting
node. Instead, J1939 uses the PGN 59904 (H0EAxx where xx is the destination node number) to
request data from remote nodes:
e.g.
Request PGN 65248 (HFEE0) from the network
PGN 59904 default priority = 06
Requesters node number = nn
ttype
Function Mode [BFM #21]
Description
K1939
K0
When BFM #20 bit 0 is set to ON, the message is always transmitted.
K1
When BFM #20 bit 0 is set to ON, the message is transmitted.
However, if data has not been changed, it is not transmitted.
K2
When the cycle time set by an interval parameter elapses, the message is always
transmitted.
K3
When the cycle time set by an interval parameter elapses, the message is transmitted.
However, if data has not been changed, it is not transmitted.
K4
The message transmits on one of the following conditions.
•
PGN Request
*2
•
Message transmit trigger flags
The message transmits when the corresponding message transmit trigger flag in
BFM #1280 to #1284 is set to ON.
For the message transmit trigger flag, refer to Section 5.20
K-1
Receive message
ttype
Communication Method
Communication Method
DLC
≤
8
DLC > 8
K-1, K0 to K4
J1939
Single Frame message
Point-to-point or BAM
(Multi message)
CAN-ID Request Message
Data Length
(DLC)
Data
Destination Node
1st Data
Byte
2nd Data
Byte
3rd Data
Byte
0x06EA18nn
3
0xE0
0xFE
0x00
24 (H18)
0x06EAFFnn
3
0xE0
0xFE
0x00
HFF = BC (Broadcast)