AH500 Programming Manual b 31 b 0 Sign bit 0: Positive 1: Negative Equation: ( ) 127 ; .1 2 1 = Ч Ч − − B M B E S The single-precision floating-point numbers range from ±2 -126 to ±2 +128 , and correspond to the range from ±1.1755Ч10 -38 to ±3.4028Ч10 +38 . The AH500 series PLC uses two consecutive registers to form a 32-bit floating-point number. Take (D1, D0) for example. D1(b15~b0) D0(b15~b0) 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 b0 b1 b2 b3 b4 b5 b6 b20 b21 b22 b23 b24 b28 b29 b30 b31 Exponent ( 8 bits) Mantissa (23bits) The position w here the d eci mal point is hid den Mantissa sign bit (0: Positive; 1: Negative) W hen b0~b31 are zeros, the content is zero.
2.2.2.2 Double-precision Floating-point Numbers The floating-point number is represented by the 64-bit register. The representation adopts the IEEE754 standard, and the format is as follows. b 63 b 0 Sign bit 0: Positive 1: Negative Equation: ( ) 1023 ; .1 2 1 = Ч Ч − − B M B E S The double-precision floating-point numbers range from ±2 -1022 to ±2 +1024 , and correspond to the range from ±2.2250Ч10 -308 to ±1.7976Ч10 +308 . The AH500 series PLC uses four consecutive registers to form a 64-bit floating-point number. Take (D3, D2, D1, D0) for example.
D3(b15~b0) D2~D0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 10 9 8 1 0 -1 -2 -3 -46 -47 -48 -49 -50 -51 -52 b0 b1 b2 b3 b4 b5 b6 b49 b50 b51 b52 b53 b60 b61 b62 b63 Exponent (11 bits; signed value) Mantissa (52 bits) T he position where the decimal point is hidden Mantissa sign bit (0: Positive; 1: Negative) When b0~b63 are zeros, the content is zero. Example 1: 23 is represented by the single-precision floating-point number. Step 1: Convert 23 into the binary number, i.e. 23.0=10111. Step 2: Normalize the binary number, i.e. 10111=1.0111 Ч2 4 (0111 is the mantissa, and 4 is the exponent.). Step 3: Get the value of the exponent.
∵ E-B=4→E-127=4 ∴ E=131=10000011 2 2-8 8-bit 23-bit S Exponent Mantissa S E7 E6 E5 E1 E0 A22 A21 A20 A6 A5 A4 A3 A2 A1 A0 E 11-bit 52-bit S Exponent Mantissa S E10 E9 E8 E1 E0 A51 A50 A49 A6 A5 A4 A3 A2 A1 A0