Chapter 6 Applied Instructions Symbol: S 1 ： Minuend Word/Double word S 2 ： SubtrAH500end Word/Double word D ： Difference Word/Double word Explanation: 1. The binary value in S 2 is subtracted from the binary value in S 1 , and the difference is stored in D . 2. Only the 32-bit instructions can use the 32-bit counter. 3. The Flags: SM600 (zero flag), SM601 (borrow flag), and SM602 (carry flag) 4. When the operation result is zero, SM600 is ON. Otherwise, it is OFF. 5. When a borrow occurs during the arithmetic, SM601 is ON. Otherwise, it is OFF. Example 1: The subtraction of 16-bit binary values:
When X0.0 is ON, the subtrAH500end in D10 is subtracted from the minuend in D0, and the difference is stored in D20. When the values in D0 and D10 are 100 and 10 respectively, D0 minus D10 leaves 90, and 90 is stored in D20. When the values in D0 and D10 are 16#8000 and 16#1 respectively, D0 minus D10 leaves 16#7FFF, and 16#7FFF is stored in D20. When the values in D0 and D10 are 16#1 and 16#2 respectively, D0 minus D10 leaves 16#FFFF. Since the borrow occurs during the arithmetic, SM601 is ON, and the value stored in D20 is 16#FFFF. When the values in D0 and D10 are 16#0 and 16#FFFF respectively, D0 minus D10 leaves 16#F0001.
Since the borrow occurs during the arithmetic, SM601 is ON, and the value stored in D20 is 16#1. 6-39 API Instruction code Operand Function 0101 D - P S , S , D 1 2 Subtraction of binary numbers Device X Y M S T C HC D L SM SR E PR K 16# “$” DF S 1 S 2 D Pulse instruction 16-bit instruction (7 steps) 32-bit instruction (7 steps) AH500 AH500 AH500