Upon the occurrence of an event at the REQ input, an instance of this FB type copies the sequence of characters in positions {P..P+L-1} of the IN input to the OUT output, and issues an event at the CNF output.

• Following the IEC 61131-3 convention, the index of the leftmost character position is 1.
• If P = 0, the result is the same as if P = 1.
• If P > N, where N is the number of characters in IN, the value of OUT is just the empty string ''.
• If the values of P and L are such that copying would proceed beyond the end of the IN string, copying just proceeds to the end of the string.