What's filed type for BinaryValue?

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>I tried the function that you wrote, however I got always a message saing Function argument value, type or count is invalid
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>I tried with simple quotes, double quotes and without quotes. It didn't work!
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>I find also a function like this but they told me that is used for 32 bits and not 16 bits. Any idea?
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>(CTOBIN (Chr(Asc(subs(BinaryValue, 4, 1)) + 128) + subs(BinaryValue, 3, 1) + subs(BinaryValue, 2, 1) + subs(BinaryValue, 1, 1)))
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>Regards,
>Roberto