Thomson
Thomson Electrak
®
MD Actuator - Installation Manual - 2020-02
20
5. CAN Bus information
5.1 Introduction to CANBUS SAE J1939
This document assumes the reader is familiar with the SAE J1939 standard. Terminology from the
standard is used, but not described in detail. The Electrak
®
MD actuator is compliant with the standard
J1939, and supports the following PGNs (Parameter Group Number) from the standard.
J1939-21 – Data Link Layer
•
Proprietary
A
61184
(0x00EF00)
•
Proprietary
A2 126720
(0x01EF00)
J1939-81 – Network Management
• Address Claimed/Cannot Claim
60928 (0x00EE00)
•
Commanded
Address
65240
(0x00FED8)
5.2 CANBUS SAE J1939 communications protocol
5.2.1 J1939 NAME
The Electrak MD has the following defaults for the J1939 NAME. Please refer to the SAE J1939/81
standard for more information on these parameters.
5.2.2 Address
The Electrak MD uses a default address value of 27 (0x1B). In applications where the default address is
not available, there are three additional methods in choosing a new address.
1. The Electrak MD device is arbitrary address capable, if another device with a higher priority NAME
contends for the selected address, the actuator will continue to request other addresses until it finds
one that it can claim.
2. The Electrak MD device can also use the commanded address PGN to select a specified address.
See J1939/81 for more details about address claiming.
3. In some applications it may be more convenient to select an address through hardware switches.
Activate the desired address select input by connecting it to positive and address select common
to negative. This allows the user to change the default address using the address select inputs
as defined in section 4.6.12. Activating individual select pins will create a binary adder to the default
address. This method can allow up to 8 individual actuator addresses on a single bus. The below
chart shows some examples on how this can be implemented. Note that conflicting messages
produce arbitrary execution.
J1939 NAME Defaults
Arbitrary Address Capable
Yes
Industry Group
0, Global
Vehicle System Instance
0
Vehicle System
0, Non-specific system
Function
255, Not available
ECU Instance
0, First instance
Manufacture Code
547, Thomson Linear LLC
Identity Number
1
Address Select
Address select common
Address select 3
Address select 2
Address select 1
Binary adder
Default address
Gnd
0
0
0
0
27 (0x1B)
Gnd
0
0
1
1
28 (0x1C)
Gnd
0
1
0
2
29(0x1D)
...
Gnd
1
1
1
7
34(0x22)
