Operation; J1939 Interface - IFM DTM426 Operating Instructions Manual

DTM426 DTM427
9 Operation
9.1 J1939 interface
The RFID read/write heads have a standardised SAE J1939 interface. All measured values and
parameters can be accessed via the J1939 protocol. The individual configuration can be saved in the
internal permanent memory.
Structure of the SAE J1939 protocol
The SAE J1939 protocol uses a 29-bit CAN identifier (extended frame format CAN 2.0B). A J1939
message has the following structure:
J1939 message
29-bit CAN identifier
Priority
28...26
Parameter Group Number (PGN)
Ext. Data Page
25
PDU format 1 (specific)
00h - EFh
23...16
PDU format 2 (global)
F0h - FFh
23...16
PDU format 1
This format defines a message which is sent to a defined device. In this case the PDU-specific byte
(PS) is the target address (DA) of the device. If the value of the PDU format field (PF) is between 0x00
and 0xEF, it is a PDU format 1 message.
For proprietary messages (manufacturer-specific) the PDU format value 0xEF is defined.
Ext. data page bit = 0 and data page bit = 0.
PDU format 2
This format defines a message which is sent globally. In this case the PDU specific byte (PS)
corresponds to the group extension (GE). If the value of the PDU format field (PF) is between 0xF0
and 0xFF, it is a PDU format 2 message.
For proprietary messages (manufacturer-specific) the area PDU format (PF) and group extension (GE)
0xFF00 – 0xFFFF is defined.
Ext. data page bit = 0 and data page bit = 0.
14
Parameter Group Number
(PGN)
25...8
▼
Data Page
24
Source address
7...0
PDU Format (PF)
23...16
Target Address (DA)
15...8
Group Extension (GE)
15...8
Data
User data of the message
0...8 bytes
Target address / group exten-
sion (PS)
15...8
▼