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3.
Message header description
The 29-bit CAN identifier used in J1939 is structured in the following way.
Priority
Reserved Data Page PDU Format PDU Specific Source Address
3 bits
1 bit
1 bit
8 bits
8 bits
8 bits
The proprietary format used by PKP keypads is defined as follows:
Priority = 6.
Reserved = 0.
Data page = 0.
PDU Format = EFh (the message is addressable).
PDU Specific = Destination Address.
Parameter Group Number (PGN) = 61184 (EF00h).
An example of CAN identifier of messages sent to the keypad is 18EF2100h where:
21h is the destination address (keypad)
00h is the source address.
An example of CAN identifier of messages sent by the keypad is 18EFFF21h where:
FFh refers to broadcast messages (no specific destination address)
21h is the source address (keypad).
4.
General Data Format
The proprietary protocol has defined a general format for the data fields in the PGN 61184.
The format consists of:
1 header field (2 bytes)
1 command byte
5 bytes (the remaining field) are defined specifically for each command.
The data length is 8 bytes,
unused bits and bytes are set to all 1’s (0xFF).
Byte 0
04h
Byte 1
1Bh
Byte 2
Command
Byte 3-7
Data required for each specific
command
