The ASCII standard represents each character with a byte, so it can represent 256 different characters. The string to Byte Array VI (which can be found in the String\Array\Path Conversion subpalette in the String palette) translates the string to a 1D U8 (that's a byte) array, where each element is one character. For instance, if you wire the string "ABC" into it, you'll get the array [65,66,67]. Create a for loop that will run 256 times and wire i out of the loop. Wire the resulting 1D array into the Byte Array to String VI and you'll get the entire ASCII table in one string. Also, search google for "ASCII table" for more data on this.
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