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CAN Pack

Pack individual signals into CAN message

Library

CAN Communication

Embedded Coder®/ Embedded Targets/ Host Communication

Description

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

    Note:   To use this block, you also need 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.

Other Supported Features

The CAN Pack block supports:

  • The use of Simulink Accelerator™ Rapid Accelerator mode. Using this feature, you can speed up the execution of Simulink models.

  • The use of model referencing. Using this feature, your model can include other Simulink models as modular components.

  • Code generation using Simulink Coder™ to deploy models to targets.

      Note:   Code generation is not supported if your signal information consists of signed or unsigned integers greater than 32-bits long.

For more information on these features, see the Simulink documentation.

Dialog Box

Use the Function Block Parameters dialog box to select your CAN Pack block parameters.

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.

CANdb file

This option is available if you specify that your data is input via 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.

    Note:   File names that contain non-alphanumeric characters such as equal signs, ampersands, and so forth are not valid CAN database file names. You can use periods in your database name. Rename CAN database files with non-alphanumeric characters before you use them.

Message list

This option is available if you specify that your data is input via 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 in unavailable 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 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.

Signals Table

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

If you are using a CANdb file, the data in the file populates this table automatically 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 manually in this table. Each signal you create has the following 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 the following options:

  • LE: Where the byte order is in little-endian format (Intel®). In this format you count bits from the start, which is the least significant bit, to the most significant bit, which has the highest bit index. 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

  • BE: Where byte order is in big-endian format (Motorola®). In this format you count bits from the start, which is 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

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 timestep:

  • Standard: The signal is packed at each timestep.

  • 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 four signals with the following types and values.

Signal NameMultiplex TypeMultiplex Value
Signal-AStandardN/A
Signal-BMultiplexed1
Signal-CMultiplexed0
Signal-DMultiplexorN/A

In this example:

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

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

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

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

Multiplex value

This option is available only if you have selected the Multiplex type to be Multiplexed. The value you provide here 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. See Conversion Formula to understand how physical values are converted to raw values packed into a message.

Offset

Specify the Offset value to apply to convert the physical value (signal value) to the raw value packed in the message. See Conversion Formula to understand how physical values are converted to raw values packed into a message.

Min

Specify the minimum physical value of the signal. The default value is -inf (negative infinity). You can specify a number for the minimum value. See Conversion Formula to understand how physical values are converted to raw values packed into a message.

Max

Specify the maximum physical value of the signal. The default value is inf. You can specify a number for the maximum value. See Conversion Formula to understand how physical values are converted to raw values packed into a message.

Conversion Formula

The conversion formula is

raw_value = (physical_value - Offset) / Factor

where physical_value is the value of the signal after it is saturated using the specified Min and Max values. raw_value is the packed signal value.

See Also

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