Unity pro (String to array of bytes)

I have tag data type is String consist of 22 characters, i want to extract character and convert into Byte to do some calculations, i have used( MID_INT) Function Block extracts a sub-string of characters starting from a certain rank. The result is a character string but I want to Array of strings or Array of Bytes and take every Byte to do some calculations.

Is There any function Block can i use it? Thanks