Definitions:
International Organization for Standardization = ISO
CAN in Automation = CiA
Fleet Management System = FMS
Controller Area Network (CAN)
Three CAN bus interfaces are assigned on the parameterizable special module (PSM) control unit (N26/15):
Interior CAN (CAN B)
Peripheral device CAN (CAN AE), fulfills the CiA 447-3 standard (additional devices for motor vehicles).
Body manufacturer CAN (CAN ABH), fulfills the FMS v1.0 and ISO11992-2/3 standard.
Data exchange is possible via the discrete inputs and outputs. The data that can be queried via CAN is listed in the "K matrix" in the documents "CAN matrix, PSM function".
CiA is the user and manufacturer group for CAN. The CiA members set up the CiA 447 standard. The objective of this standard is the manufacturer-independent standardization of the electronic interfaces for special equipment used in vehicles.
Specification:
"Highspeed CAN class C", "Extended CAN Identifier" (29 bit)
Baud rate: 125 kBit/s
Signal format: Intel ("Least significant bit first" = "LSB")
Nominal voltage: 5 V
Transceiver: "TJA1043"
Terminating resistor for PSM control unit: 60 Ω
All CAN content can be activated separately and independent of each other per coding.
Coding for enabling of body manufacturer CAN
The following parameters must be set if the body manufacturer CAN is used:
Activation of body manufacturer CAN
FMS, ISO or HYBRID message packages
Baud rate 125, 250 or 500 kBit/s
Activation of freely assignable messages (only ISO, HYBRID)
Input:
The transmission and reception of CAN signals CAN be switched on and off dynamically on the body manufacturer CAN with the aid of the internal input "ABH_INPUT_COMM_ENABLE".
If CAN signals are to be sent or received continuous, this can be done by connecting, e.g. the following signal IDs to the input "ABH_INPUT_COMM_ENABLE":
#1044 ("Interior CAN bus" status): PSM sends and receives CAN signals to the body manufacturer CAN as soon as the interior CAN bus is active.
#1219 (Status of circuit 15): Retarder sends and receives CAN signals to the body manufacturer CAN as soon as circuit 15 is active.
Fleet management system
The fleet management system only contains messages to be sent by the PSM control unit. These messages contain the following information, for example:
Vehicle speed
Engine values
Driver information
To use the fleet management system, a baud rate of 250 kBit/s must be set for the body manufacturer CAN.
ISO11992-2/3
This standard contains send and receive messages. The send messages contain information similar to that for the fleet management system, with the addition of some engine information. The signals received from the PSM control unit are stored in a signal pool and can be used, e.g. for working speed control.
Freely assignable messages
The freely assignable messages are output as follows:
In the send direction, 4 messages ("GPM_1H", "GPM_1I", "GPM_1J", "GPM_1K")
In the receive direction: 4 messages ("GPM_2H", "GPM_2I", "GPM_2J", "GPM_2K")
In order to send signals on the body manufacturer CAN, the corresponding inputs of the "body manufacturer CAN bus" module must be assigned appropriate signals from the signal pool. The receive signals are stored in the signal pool to await further use. The signals are designated as "AuxBit", "AuxByte" etc.
Details can be found in the documents "Signal lists, PSM function".
Activation of the freely assignable messages is only possible if the message package ISO11992-2/3 has also been activated. Otherwise, the send messages of the PSM control unit ("GPM_1H", "GPM_1I", "GPM_1J" and "GPM_1K") are not sent.
Structure of messages:
8 bit signals
2 byte signals
2 2-byte signals
Cycle times of sent messages:
2x with 100 ms
1x with 500 ms
1x with 1000 ms
Other contents are listed in the "CAN matrix" in the documents "CAN matrix, PSM function".
Coding for peripheral device CAN enable
The following parameters must be set when using the peripheral device CAN:
Peripheral device CAN active or inactive, satisfies the CiA 447-3 standard.
Baud rate 125 kBit/s.
Referenced documents
- gf5421d9998tsa Overview of system components for parameterizable special module (PSM)