Stream Input
Read formatted ASCII data from communication channel
Libraries:
Simulink Desktop Real-Time
Description
The Stream Input block reads formatted ASCII data from a port or file. After you have added a Stream Input block to your model, double-click the Stream Input block to open the Block Parameters: Stream Input dialog box.
The driver must be one of:
Standard Devices > File
Standard Devices > Serial Port
Standard Devices > TCP Protocol
Standard Devices > UDP Protocol
Specify parameter values as required, then click OK or Apply. When you install a UDP device, enter port addresses in decimal format in the Standard Devices UDP Protocol dialog box.
Examples
Stream Input/Output
Transfer data through TCP communication protocol by using ASCII encoding.
Ports
Output
Output Data — Data received from communication channel
numeric vector | string
Data values that were received from the communication channel as formatted ASCII data and decoded according to Format string.
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.
Missed Ticks — Missed tick count (optional)
double
In Connected IO mode, 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 >
.
For more information about driver support for I/O boards, see Hardware Support from Simulink Desktop Real-Time.
Dependency
When you select a board in the list of registered boards, the Delete current board and Board setup buttons are available.
Programmatic Use
Block Parameter:
DrvName |
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.
Programmatic Use
Block Parameter:
DrvName |
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.
Programmatic Use
Block Parameter:
DrvAddress |
Block Parameter:
DrvOptions |
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.
Programmatic Use
Block Parameter:
SampleTime |
Maximum missed ticks — Number of timer ticks by which your model can trail the kernel
10
(default) | integer
In Connected IO mode, 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 Run in Kernel mode, the software ignores this value.
Programmatic Use
Block
Parameter:
MaxMissedTicks |
Show “Missed Ticks” port — Send number of missed ticks to port Missed Ticks
'off'
(default) | 'on'
In Connected IO mode, select this check box to send the number of missed
ticks to output port Missed Ticks
.
In Run in Kernel mode, the Missed Ticks
port is
zero.
Programmatic Use
Block Parameter:
ShowMissedTicks |
Yield CPU when waiting — Yield CPU while kernel waits for hardware
'off'
(default) | 'on'
In Connected IO mode, select this check box to grant other programs more CPU time while the kernel waits for a response from the hardware.
In Run in Kernel mode, the software ignores this value.
Programmatic Use
Block Parameter:
YieldWhenWaiting |
Block output data types — Output type and grouping of data sent to the block outputs
'double'
(default) | character vector | cell array of character vector
A character vector or a cell array of character vectors. The
block has as many output ports as the number of character vectors.
Each vector specifies a data type by name, and optionally the number
of items of that data type in an output vector. For example, 'double'
means
one double
value, and '4*int8'
means
four int8
values.
The values made available on output ports are grouped and typed
according to the Block output data types character
vectors. For example, if Block output data types is {'2*int8','3*double'}
,
the block outputs:
On output port
1
— anint8
vector of width2
On output port
2
— adouble
vector of width3
Programmatic Use
Block Parameter:
DataTypes |
Format string — Format of data items being read from the stream
'%f'
(default) | character vector
A specification in the same format used by C library I/O routines like
scanf
. The format string describes the data to be
received. The number of elements in the format string must equal the number
of data items specified in Block output data types. If
the specifier is %s
or %c
for string,
the created output port of type string only produces string signals. The
Block output data types
parameter value for this
output port must be "1"
, because strings can only be
scalars.
For example, assume that Block output data types is {'2*int8','3*double'}
and Format
string is '%d %d %f %f %f'
. The block
reads an ASCII representation of two integers and three doubles. The
block makes the resulting values available to the application on:
Output port
1
— anint8
vector of width2
Output port
2
— adouble
vector of width3
If the data type specified for a value in Block output data types differs from the type of the corresponding element in Format string, type conversion occurs. The block reads data as specified by Format string, converts the data to match the Block output data types, and provides the data to the application on the block output ports.
Programmatic Use
Block Parameter:
FormatString |
Message termination — Specify end of message
{'\r', '\n'}
(default) | character vector | cell array of character vector | integer
A character vector, cell array of character vectors, or a number. If the value is a character vector, receiving this sequence of characters terminates data input. If the value is a cell array, any character vector in the cell array terminates data input. If the value is a number, data input terminates after reading the specified number of characters.
Programmatic Use
Block Parameter:
Terminator |
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.
Programmatic Use
Block Parameter:
ShowReady |
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.
Programmatic Use
Block Parameter:
ShowError |
Version History
Introduced in R2007bR2024b: Update to blocks with port names
In R2024b, when you enable optional ports, such as Show "Missed Ticks" port, these Simulink® Desktop Real-Time™ block ports appear with labels.
R2019b: Stream Input and Stream Output Blocks Support String Signals
The Stream Input block and Stream Output block support Simulink string signals.
R2019a: RS-232 Serial Port Drivers Support for macOS
The serial port drivers for the Packet Input block, Packet Output block, Stream Input block, and Stream Output block support macOS systems. In previous releases, the serial port drivers for these blocks supported Windows® systems only.
R2018a: TCP and UDP Protocol Support for Stream Input and Stream Output
The TCP protocol and UDP protocol drivers for the Stream Input block and Stream Output block are available from the Standard Devices list. From the Install new board button, select Standard Devices > TCP Protocol or select Standard Devices > UDP Protocol.
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