You are getting 昀䟼 竾ᩅ蜁䘑Ƃﲰ
耂䘖˨ཅ��䘓ɚ孈⌃䏞͛꘨궅㰃䔋ϯﲈᢆ䟩Л퐌ᡃᄄ䞭ҕ텎ꅆ匄䗐Ӵ쉲效ꔄ" when you open a .dat file because the file is being opened in text mode. The contents though are same the format of display will be different based on which format you open the file in. ie binary, text etc.
However i came across a thred where the same question as you asked here was asked, and a solution was provided for it in vb. This might help but the thing is, even in that code, the method they followed it extract detail from .txt file and store in .dat file making use of CSng option.
.txt to .dat conversion[
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