System Description; Message Format In The Sae J1939 Network - Balluff BMD 1E NJ5-Serie Konfigurationsanleitung

BMD 1E_ _-_ _ _ _/_ _ _-NJ5...
Microwave Position Sensor
2

System description

The SAE J1939 communication module implemented in
the BMD microwave position sensor converts the
measurement data acquired in the BMD into SAE J1939
messages and sends them into the SAE J1939 network.
PGNs in PDU1 and PDU2 format are used.
2.1

Message format in the SAE J1939 network

An SAE J1939 network uses an expanded CAN-29-bit
identifier (CAN-ID). The entire resulting CAN message is
illustrated in Fig. 2-1. The CAN-ID contains in an SAE
J1939 network the priority and Parameter Group Number
(PGN) as well as the Source Address of the sending node.
The PGN indicates the meaning of the data in the data
field.
In the SAE J1939 network the PGNs are divided into two
PDU formats, the PDU1 and PDU2 format. PDU1 format is
used when the field PDU-Format within the PGN assumes
a value less than 0xF0 (240 ), and PDU2 format when the
10
value is greater.
If a PGN has PDU1 format, the field PDU Specific contains
the destination address of the message. Peer-to-Peer-
communication takes place. Since in PDU1 format the field
PDU Specific only contains the destination address and is
not needed for interpreting the data, the PGN in PDU1
format is given without PDU Specific.
With PDU2 format the field PDU Specific may assume any
value between 0x00 and 0xFF (0...255
then takes place via a Broadcast, which means the
message is addressed to all slaves in the SAE J1939
network. The maximum data length within a message is 8
bytes.
S
29 Bit
O
CAN ID
F
3 Bit
Priority
Fig. 2-1: Message format in the SAE J1939 network
www.balluff.com
). Communication
10
R
6 Bit 0...8 byte
T
Control Field Data Field
R
8 Bit
18 Bit
Source
PGN
Address
1 Bit 1 Bit
Reserved Data Page PDU Format
16 Bit 2 Bit
CRC Field ACK End of Frame
8 Bit 8 Bit
PDU Specific
7 Bit
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