AH500 Programming Manual Example 2: ： The addition of 32-bit binary values: When X0.0 is ON, the subtrAH500end in (D41, D40) is subtracted from the minuend in (D31, D30), and sum is stored in (D51, D50). (The data in D30, D40, and D50 is the lower 16-bit data, whereas the data in D31, D41, and D51 is the higher 16-bit data). When the values in (D31, D30) and (D41, D40) are 55555555 and 11111111 respectively, (D31, D30) minus (D41, D40) D10 leaves 44444444, and 44444444 is stored in (D51, D50). When the values in (D31, D30) and (D41, D40) are 16#80000000 and 16#FFFFFFFF respectively, (D31, D30) minus (D41, D40) leaves 16#F80000001.
Since the borrow occurs during the arithmetic, SM601 is ON, and the value stored in (D51, D50) is 16#80000001. 6-40