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Serial Transmit

Send buffered data to the specified serial port


Simulink Support Package for Arduino® Hardware


Send buffered data to the specified serial port. For more information, see Use Serial Communications with Arduino Hardware.

The Arduino Uno hardware has one serial port device, serial port 0, connected to the digital pins marked TX 0 and RX 0. If you set the Port number parameter to 0, this block transmits over the digital pin marked TX 0.

The block input accepts vector or scalar data of datatypes, uint8, int8, uint16, int16, uint32, int32, double, single, or boolean.

During simulations without the hardware, this block does nothing.

If you use this block in models with the Standard Servo Read, Standard Servo Write, and Continuous Servo Write blocks, use longer sample times to avoid overruns.


Do not connect the serial port pins to an RS-232 serial interface, such as the DE-9M connector on a computer, without limiting the voltage. The RS-232 standard allows higher voltages that can damage your hardware. For details, read the documentation for your Arduino hardware.


The double datatype occupies 8 bytes (64 bit) on the Arduino Due board and it occupies 4 bytes (32 bit) on the other Arduino boards.


Port Number

Enter the number of the serial port.

Click View pin map to open the Arduino Pin Mapping table.

To know about the fixed ports and the allocated pins for the block, see Pin Mapping for Arduino Timer Independent Blocks.

You can assign a Serial Transmit block and a Serial Receive block to the same serial port.

Do not assign multiple Serial Transmit blocks to the same serial port.

Do not assign the pin numbers used by the serial port to other blocks within the model.

Serial port 0 is connected to the USB port through a converter. Do not use both serial port 0 and the USB port at the same time. For example, do not use serial port 0 if you intend to use External mode, because External mode requires the USB port.

Send mode

Select the mode in which you want to send the data.

Select write option to write the raw data to the serial port.

Select print option to print the formatted data to the serial port as ASCII text.

Select println option to print the formatted data to the serial port as ASCII text followed by a carriage return character '\r'( ASCII 13) and a newline character '\n'(ASCII 10).


Enter the label/header text for the data that you want to print.


Select the format in which you want to print the data. You can select the Decimal, Hexadecimal,Binary, or the Octal option for data to print. Decimal is the default option.


Enter the precision value for the Decimal data format. 2 is the default option.

This parameter is available only when you select Decimal option in Format parameter.