How can I programmatically detect the baudrate settings of a COM port?

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I know COM Port settings can be read and set using the Device Manager. However, I need to be able to obtain the BaudRate programmatically.

What I have tried:

I noticed that *some* COM Ports settings are included in the Win32_SerialPortConfiguration but most are not included.

Posted 28-Mar-22 4:19am

Bruce Ramsland

Updated 28-Mar-22 5:09am

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OriginalGriff · Answer 1 · 2022-03-28T04:57:00

You can't get a baudrate, unless you have set it - it's not a "feature" that is transmitted as part of the communication between two devices unless they actively have a "negotiation phase" which is unbelievably rare and mostly only found in embedded devices, not OSes.

Baudrate is the speed in bits per second at which a device transmits - and the "other end" needs to be set to the same speed (plus or minus 5%) in order to reliably understand what is being sent. It's a "internal" feature that you can set in software but you can only read back the value you set (or the default value set by the port software which for the C# SerialPort class is 9600 baud).
There is no way to "read" the baudrate of the remote device as they can't communicate reliably unless they are both set to the same value!

Richard MacCutchan · Answer 2 · 2022-03-28T05:09:00

Solution 2

If you are talking about a Windows system then you can use GetCommConfig function (winbase.h) - Win32 apps | Microsoft Docs[^].

Posted 28-Mar-22 5:09am

Richard MacCutchan