qextserialport taking value 0 as null ?

[calhal]

What's the difference between NULL and 0x00?

You have

char buff[2];

char buff[2];

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and then you read some unknown number of characters. Are you sure there are only two to read?

Are you sure, that all the characters (whole frame) are read before you use QTextBrowser::append() ? If not, you'll see some characters in new line every time you run this code.