Digital Input (Single Sample)
Acquire single sample from multiple digital lines of data acquisition device
Data Acquisition Toolbox
The Digital Input (Single Sample) block synchronously outputs the latest scan of data available from the digital lines selected at each simulation time step. It acquires unbuffered digital data, and delivers this as a vector of boolean values.
The block has no input ports. It has one or more output ports, depending on the option you choose in its dialog box.
The block inherits the sample time of the model. Digital input acquisition is done synchronously, according to the following diagram.
At the first time step (T1), data is acquired from the selected hardware lines. The simulation does not continue until data is read from all lines.
To use this block, you need both Data Acquisition Toolbox™ and Simulink® software.
Some devices are not supported by the Simulink blocks in Data Acquisition Toolbox. To see if your device supports Simulink, refer to Supported Hardware.
Other Supported Features
This block supports the use of Simulink Accelerator™ mode, but not Rapid Accelerator or code generation.
The block supports the use of model referencing, so that your model can include other Simulink models as modular components.
For more information on these features, see the Simulink documentation.
Data — Acquired digital input
Acquired digital input data, returned as booleans. If using only one output port for all lines, the output is a 1-by-N vector for N channels. If using a port for each line, each scan results in a single boolean on each port. Multiple ports are named by line names or device specified line IDs.
Timestamp — Timestamp of scan
Timestamp of scan, returned as a double. This port is available when you check the Output timestamp parameter.
Device — Device from which you want to acquire data
The device from which you want to acquire data. The items in the list vary,
depending on which devices you have connected to your system. Devices in the list are
specified by adaptor or vendor name and unique device ID, followed by the model name of
the device, for example,
ni Dev1 (USB-6255). The first available
device is selected by default. A CompactDAQ chassis would be shown as a single device
identified by vendor name, chassis ID, and chassis model; for example,
Lines — Device line selection and configuration
options depend on device
Line ID — ID of the hardware line (for example, port0/line0). This is automatically detected and filled in by the selected device, and is read-only.
Name — Hardware line name. This is automatically detected and filled in from the hardware, though you can edit the name.
Module — Device ID that the line belongs to. The Module column is read-only. If a CompactDAQ chassis is selected, it shows the ID of the CompactDAQ module which the line belongs to; otherwise the ID of the device.
Number of ports — Number of output data ports
1 for all lines | 1 per line
Number of output data ports, specified as:
1 for all lines — The block has only one output port for all of the lines that are selected in the table. Acquired data is returned as a 1-by-N vector of boolean values, whose size is the number of lines.
1 per line — The block has one output port per selected
line. Data is returned as a 1-by-1 boolean value on each port. The name of each output
port is the name specified in the table for each line. If no name is provided, the name
is the Line ID. For example, if line 2 of hardware port 3 is selected, and you did not
specify a name in the line table,
port3/line2 appears in the block.
Data size for each line is 1-by-1.
Sample time — Block execution rate
Specifies the sample time of the block during the simulation. This is the rate at which the block is executed during simulation. The default value is 1 (seconds). For more information, see What Is Sample Time? (Simulink).
Output timestamp — Add timestamp output port
Select this option to output the absolute timestamp of the scan. This option adds a
new output port to the block. The data type of this port is double (datenum), which
corresponds to a serial date number. You can convert the datenum into a datetime value