CAN Pack

Pack individual signals into CAN message

Library

Vehicle Network Toolbox™ > CAN Communication

Embedded Coder® > Embedded Targets > Host Communication

  • CAN Pack block

Description

The CAN Pack block loads signal data into a message at specified intervals during the simulation.

To use this block, you must have a license for Simulink® software.

CAN Pack block has one input port by default. The number of block inputs is dynamic and depends on the number of signals you specify for the block. For example, if your block has four signals, it has four block inputs.

This block has one output port, CAN Msg. The CAN Pack block takes the specified input parameters and packs the signals into a message.

The CAN Pack block supports:

  • Simulink Accelerator™ rapid accelerator mode. You can speed up the execution of Simulink models.

  • Model referencing. Your model can include other Simulink models as modular components.

  • Code generation to deploy models to targets. If your signal information consists of signed or unsigned integers greater than 32 bits long, code generation is not supported.

For more information, see Design Your Model for Effective Acceleration (Simulink).

Dialog Box

To select your CAN Pack block parameters, use the Function Block Parameters dialog box.

Parameters

Data is input as

Select your data signal:

  • raw data: Input data as a uint8 vector array. If you select this option, you only specify the message fields. all other signal parameter fields are unavailable. This option opens only one input port on your block.

  • manually specified signals: Allows you to specify data signal definitions. If you select this option, use the Signals table to create your signals. The number of block inputs depends on the number of signals you specify.

  • CANdb specified signals: Allows you to specify a CAN database file that contains message and signal definitions. If you select this option, select a CANdb file. The number of block inputs depends on the number of signals specified in the CANdb file for the selected message.

The block supports the following input signal data types: single, double, int8, int16, int32, int64, uint8, uint16, uint32, uint64, and boolean. The block does not support fixed-point data types.

CANdb file

This option is available if you specify that your data is input through a CANdb file in the Data is input as list. Click Browse to find the CANdb file on your system. The message list specified in the CANdb file populates the Message section of the dialog box. The CANdb file also populates the Signals table for the selected message.

File names that contain non-alphanumeric characters such as equal signs, ampersands, and so on are not valid CAN database file names. You can use periods in your database name. Before you use the CAN database files, rename them with non-alphanumeric characters.

Message list

This option is available if you specify that your data is input through a CANdb file in the Data is input as field and you select a CANdb file in the CANdb file field. Select the message to display signal details in the Signals table.

Message

Name

Specify a name for your CAN message. The default is CAN Msg. This option is available if you choose to input raw data or manually specify signals. This option is not available if you choose to use signals from a CANdb file.

Identifier type

Specify whether your CAN message identifier is a Standard or an Extended type. The default is Standard. A standard identifier is an 11-bit identifier and an extended identifier is a 29-bit identifier. This option is available if you choose to input raw data or manually specify signals. For CANdb specified signals, the Identifier type inherits the type from the database.

Identifier

Specify your CAN message ID. This number must be a positive integer from 0 through 2047 for a standard identifier and from 0 through 536870911 for an extended identifier. You can also specify hexadecimal values by using the hex2dec function. This option is available if you choose to input raw data or manually specify signals.

Length (bytes)

Specify the length of your CAN message from 0 to 8 bytes. If you are using CANdb specified signals for your data input, the CANdb file defines the length of your message. If not, this field defaults to 8. This option is available if you choose to input raw data or manually specify signals.

Remote frame

Specify the CAN message as a remote frame.

Output as bus

Select this option for the block to output CAN messages as a Simulink bus signal. For more information on Simulink bus objects, see Composite Signals (Simulink).

Signals Table

This table appears if you choose to specify signals manually or define signals by using a CANdb file.

If you are using a CANdb file, the data in the file populates this table and you cannot edit the fields. To edit signal information, switch to manually specified signals.

If you have selected to specify signals manually, create your signals in this table. Each signal that you create has these values:

Name

Specify a descriptive name for your signal. The Simulink block in your model displays this name. The default is Signal [row number].

Start bit

Specify the start bit of the data. The start bit is the least significant bit counted from the start of the message data. The start bit must be an integer from 0 through 63.

Length (bits)

Specify the number of bits the signal occupies in the message. The length must be an integer from 1 through 64.

Byte order

Select either of these options:

  • LE: Where the byte order is in little-endian format (Intel®). In this format you count bits from the least significant bit, to the most significant bit. For example, if you pack one byte of data in little-endian format, with the start bit at 20, the data bit table resembles this figure.

    Little-Endian Byte Order Counted from the Least-Significant Bit to the Highest Address

    Image of little-endian byte order from least-significant bit to highest address

  • BE: Where byte order is in big-endian format (Motorola®). In this format you count bits from the least-significant bit to the most-significant bit. For example, if you pack one byte of data in big-endian format, with the start bit at 20, the data bit table resembles this figure.

    Big-Endian Byte Order Counted from the Least Significant Bit to the Lowest Address

    Image of big-endian byte order from least-significant bit to lowest address

Data type

Specify how the signal interprets the data in the allocated bits. Choose from:

  • signed (default)

  • unsigned

  • single

  • double

Multiplex type

Specify how the block packs the signals into the CAN message at each time step:

  • Standard: The signal is packed at each time step.

  • Multiplexor: The Multiplexor signal, or the mode signal is packed. You can specify only one Multiplexor signal per message.

  • Multiplexed: The signal is packed if the value of the Multiplexor signal (mode signal) at run time matches the configured Multiplex value of this signal.

For example, a message has these signals with the following types and values.

Signal NameMultiplex TypeMultiplex Value
Signal-AStandardNot applicable
Signal-BMultiplexed1
Signal-CMultiplexed0
Signal-DMultiplexorNot applicable

In this example:

  • The block packs Signal-A (Standard signal) and Signal-D (Multiplexor signal) in every time step.

  • If the value of Signal-D is 1 at a particular time step, then the block packs Signal-B along with Signal-A and Signal-D in that time step.

  • If the value of Signal-D is 0 at a particular time step, then the block packs Signal-C along with Signal-A and Signal-D in that time step.

  • If the value of Signal-D is not 1 or 0, the block does not pack either of the Multiplexed signals in that time step.

Multiplex value

This option is available only if you have selected the Multiplex type to be Multiplexed. The value you provide must match the Multiplexor signal value at run time for the block to pack the Multiplexed signal. The Multiplex value must be a positive integer or zero.

Factor

Specify the Factor value to apply to convert the physical value (signal value) to the raw value packed in the message. For more information, see Conversion Formula.

Offset

Specify the Offset value to apply to convert the physical value (signal value) to the raw value packed in the message. For more information, see Conversion Formula.

Min, Max

Define a range of signal values. The default settings are -Inf (negative infinity) and Inf, respectively. For CANdb specified signals, these settings are read from the CAN database. For manually specified signals, you can specify the minimum and maximum physical value of the signal. By default, these settings do not clip signal values that exceed the settings.

Conversion Formula

The conversion formula is:

raw_value = (physical_value - Offset) / Factor
where physical_value is the original value of the signal and raw_value is the packed signal value.

See Also

Blocks

Functions

Introduced in R2009a