Packet Input

Read binary data or a CAN message from a communication channel

• Library:

• Simulink Desktop Real-Time

• 

Description

Read unformatted binary data from a port or file. After you add a Packet Input block to your model, double-click the block to set its parameters.

The driver must be one of:

• Standard Devices > File

• Standard Devices > Serial Port

• Standard Devices > TCP Protocol

• Standard Devices > UDP Protocol

• Kvaser > CAN Device

• PEAK-System > CAN Device

• Vector > CAN Device

• MathWorks > virtual CAN (requires Vehicle Network Toolbox™)

When you install a UDP device, enter port addresses in decimal format in the Standard Devices UDP Protocol dialog box.

Ports

Output

Output Data — Data received from communication channel

vector

Data values that were received from the communication channel as unformatted binary data. For CAN or Virtual CAN devices, this port supports:

• CAN_MESSAGE datatype

• CAN_MESSAGE_BUS datatype

• CAN_FD_MESSAGE_BUS datatype in CAN FD mode

Data Ready — Data ready port (optional)

1 | 0

This port signals 1 if the block has new data available and 0 otherwise.

Dependency

When you select Show “Data Ready” port, this port is visible.

Data Error — Data error port (optional)

1 | 0

This port signals 1 if a data error occurs and 0 otherwise.

Dependency

When you select Show “Data Error” port, this port is visible.

Timestamp — Packet timestamp port (optional)

double

This port shows the timestamp for the CAN message packets.

Dependency

When you select Show packet timestamp port, this port is visible.

Missed Ticks — Missed tick count (optional)

double

In normal or accelerator modes, returns the number of timer ticks that your model lags behind the real-time kernel. When the model lags by more than Maximum missed ticks, the software reports an error and simulation stops.

Dependency

When you select Show “Missed Ticks” port, this port is visible.

Data Types: double

Parameters

Install new board — Register a board

< no board selected > (default)

When you click Install new board, the software displays a list of manufacturers of supported boards. When you select a manufacturer, the software displays a list of boards available from that manufacturer. When you select a board, the software adds the board to the list of registered boards and makes that board the current board.

By default, the initial selection in the list of registered boards is < no board selected >.

Dependency

When you select a board in the list of registered boards, the Delete current board and Board setup buttons are available.

Delete current board — Delete the current board

(button)

To delete the current board, click this button. The initial selection of the list of registered boards changes to < no board selected >.

Dependency

To activate this parameter, select a board in the list of registered boards.

When you delete the current board, the Delete current board and Board setup buttons are no longer available.

Board setup — Set up the board

(button)

To set up the board, click this button.

A board-specific dialog box opens to set up the board. For more information, see the board manufacturer documentation.

Dependency

To activate this parameter, select a board in the list of registered boards.

To deactivate this parameter, click Delete current board.

Sample time — Sample time of block

0.1 (default) | double

Enter a value, in seconds, that represents how frequently you want the block to execute and interact with the I/O hardware. The block synchronizes your model with the real-time clock at this sample rate.

If you are using a fixed-step solver, enter the value that you entered as the Fixed step size configuration parameter or an integer multiple of that value.

Maximum missed ticks — Number of timer ticks by which your model can trail the kernel

10 (default) | integer

In normal or accelerator modes, enter the number of timer ticks that your model can lag behind the real-time kernel. When the model lags behind by this number or fewer timer ticks, the software assumes that the lag is temporary. It allows the model to catch up, even if the model misses some ticks. When the model lags by more than this number, the software reports an error and simulation stops.

In external mode, the software ignores this value.

Show “Missed Ticks” port — Send number of missed ticks to port Missed Ticks

'off' (default) | 'on'

In normal or accelerator modes, select this check box to send the number of missed ticks to output port Missed Ticks.

In external mode, the Missed Ticks port is zero.

Yield CPU when waiting — Yield CPU while kernel waits for hardware

'off' (default) | 'on'

In normal or accelerator modes, select this check box to grant other programs more CPU time while the kernel waits for a response from the hardware.

In external mode, the software ignores this value.

Packet identifier — Identifier of the packet

1 (default) | vector

Enter the ID of the packet to process. If your protocol does not have packet IDs, this parameter is disabled.

Extended identifier — Extended identifier of the packet (CAN boards only)

'off' (default) | 'on'

Select this check box if Packet identifier is an extended identifier.

Input packet size — Number of bytes that each input packet contains

32 (default) | integer

Enter the number of bytes expected in each input packet. This number must match the number of bytes required by the type specifications in Block output data types.

Block output data types — Output type and grouping of data from the packet

'4*double' (default) | character vector | cell array of character vector

One or more character vectors that specify how the data in each packet is to be typed and grouped for input to the application. The Packet Input block has an output port corresponding to each character vector in Block output data types. Changing the number of character vectors changes the number of output ports.

Each character vector has the format [n*]datatype. The data that the character vector describes has the type specified by datatype and the width specified by n. If n is not specified, the width is 1. For example, 'double' means one double value, and '4*int8' means a vector of four int8 values. You can also type 'CAN_MESSAGE' to specify a single CAN_MESSAGE value.

By providing a cell array of such character vectors, you can convert an input packet into the types required, packaged into vectors. For example, specifying {'int16','int16','double'} creates three ports. The first and second each output an int16 value, and the third outputs a double. Specifying {'2*int16','double'} creates two ports: a vector of two int16 values, and a scalar double.

The block forces an out-of-range value to the maximum value for that data type.

Input packet field byte order — Byte order of packet acquired from device

Little Endian (default) | Big Endian

From the list, select:

• Little Endian (default) — Send multibyte values in little-endian format.

• Big Endian — Send multibyte values in big-endian format.

Show “Data Ready” port — Add port Data Ready that signals 1 when data is available

'off' (default) | 'on'

When you select this check box, the block makes visible the output port Data Ready. This port signals 1 when the block has new data available and 0 otherwise.

Show “Data Error” port — Add port Data Error that signals 1 if error occurs

'off' (default) | 'on'

When you select this check box, the block makes visible the output port Data Error. This port signals 1 when a data error occurs and 0 otherwise.

Show packet timestamp port — Add port Timestamp that outputs CAN message timestamps

'off' (default) | 'on'

When you select this check box, the block makes visible the output port Timestamp. This port shows the timestamps for the CAN message packets. If your protocol does not have packet timestamps, the block ignores this value.

Model Examples

Packet Input/Output

Transfer data through UDP communication protocol using binary encoding. The model sends data within one computer, from one UDP port to another. You can modify the model to communicate between two computers by splitting this model into its send and receive parts and running the models on two computers. The yellow blocks are used to send the data, the blue blocks are used to receive the data. Then, please enter the host names or IP addresses of the two computers into the appropriate fields in the Board Setup dialog.

CAN Input/Output

Transfer data through CAN bus. The model sends data within one computer, from one CAN channel to another. The two CAN channels can be either virtual channels or physical channels on a dual-channel CAN device. Two different CAN messages using different message identifiers are being transmitted. You can modify the model to communicate between two computers by splitting this model into its send and receive parts and running the models on two computers. The yellow blocks are used to send the data, the blue blocks are used to receive the data.

CAN Input/Output with Vehicle Network Toolbox

Transfer data through CAN bus, utilizing the CAN_MESSAGE data type and the CAN Pack and CAN Unpack blocks available in Vehicle Network Toolbox™ block library. The CAN_MESSAGE data type can be directly processed by Simulink Desktop Real-Time™ blocks.