I am developing some software on Windows which will run on Linux on an embedded ARM processor.

It will take a few weeks until the hardware arrives, but I would like to test the software now, in order to be prepared.

Is there some gratis software or Windows (preferably, but I could accept Linux), which:

  • detects any output which my program write to the serial port and displays it, so that I can verify it

  • allows me to input text to the serial port, so that I can verify that my app receives it correctly

  • must support 9900, 8, N, 1, but I don't object to flexibility & being able to specify other values :-)

  • preferably with GUI, but command line is also acceptable

  • scripting (reply to output X with input Y would be a big bonus)

1 Answer 1


For anyone else who wants to do this in future – use com0com which is a virtual serial port emulator.

The Null-modem emulator is an open source kernel-mode virtual serial port driver for Windows, available freely under GPL license.

The Null-modem emulator allows you to create an unlimited number of virtual COM port pairs and use any pair to connect one COM port based application to another. Each COM port pair provides two COM ports. The output to one port is the input from other port and vice versa.


Alternatively, you can use [Virtual Serial Port Driver]( Virtual Serial Port Driver) by Eltima Software. It allows creating a large number of virtual COM ports and gives you great possibility to emulate serial port behaviour fully. Virtual Serial Port Driver provides flexible port creation, management, and removal, allows testing the software, supports control lines and high speed of data transfer with virtual port.

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