The set command is normally used to set the value of an environment variable. This probably looks a bit confusing, so let’s break it down. The following example is a more robust version of the command shown above: Higher numbered COM ports may not be recognised when written this way, but a workaround is shown below.In this case, an additional mode command can be used to configure the baudrate (and/or other serial parameters). The serial port you’re using may not already be set to the baudrate you desire.An alternative method of sending the string without these trailing characters using the set command is shown below. The first five byte values in the sequence are just the letters of the word “hello”, but the last three are the space, carriage return and line feed characters. I tested this myself by capturing the transmitted bytes using a microcontroller and then echoing their numerical values back to the screen – the values were: “104 101 108 108 111 32 13 10”. The string that gets sent in the above example is actually 8 bytes long because it includes the trailing space character after the word “hello” as well as carriage return and line feed characters.( SerialSend provides an easy alternative method of sending strings to whatever the highest numbered available COM port is, which can be very useful.) If you’re using a USB-to-serial converter, this number may change over time, especially if you plug the device into different USB sockets. You need to know the number of the COM port you want to send to.There are a couple of potential snags though: So the string “hello” gets sent to the serial port rather than to the screen. Here however, its output is redirected (using the “>” character) to the special filename “COM1”, which is actually a serial port rather than a file on disk. The echo command is typically used to display a string in the console. You can just type this command into a normal Windows console: The simplest case is something like the following which sends the string “hello” to COM1 (the first serial port). Instead you can just use Windows’ built-in echo, set and mode commands. I actually developed a small command line utility called SerialSend for doing exactly this, but in many cases you can get away without using any special programs at all. The sort of thing I might use this for is sending a command to a robot or other microcontroller-based device that I’m building using a USB-to-serial converter. I often need to send short character strings to a serial port in Windows.
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