Mitsubishi PLC floating point operation instructions

Floating point operation instructions (FNC110-FNC1320) are used for floating point number processing. Floating point numbers are 32-bit numbers, including 13 instructions such as floating point comparison, transformation, four arithmetic operations, square root operations and trigonometric functions. All floating point processing instructions are 32-bit instructions. When used, the mnemonics of most instructions must be preceded by the 32-bit operation identifier "D". They are distributed in the instruction numbers FNC110~FNC119, FNC120~FNC129, FNC130~FNC139.

Binary floating point comparison instruction ECMP

(1) Binary floating point comparison instruction ECMP (FNC110) The use of the DECMP (P) instruction is shown in Figure 1. It compares two source operands and reflects the comparison result in the destination operand. If the operand is a constant, it is automatically converted into a binary floating point value for processing. The source operand of this instruction can be K, H and D, and the destination operand can be Y, M and S. It is a 32-bit operation instruction and occupies 17 program steps.

Figure 1 Use of binary floating point comparison instructions

Binary floating point interval comparison instruction EZCP

(2) Binary floating point range comparison instruction EZCP (FNC111) The function of the EZCP (P) instruction is to compare the content of the source operand with the range of upper and lower points specified by the binary floating point value, and the corresponding result is reflected on the target operand with ON/OFF, as shown in Figure 2. This instruction is a 32-bit operation instruction and occupies 17 program steps. The source operand can be K, H and D; the target operand is Y, M and S. [S1.] should be less than [S2.], and when the operand is a constant, it will be automatically converted into a binary floating point value for processing.

Figure 2 Use of binary floating point interval comparison instructions

Addition instruction E AD D

Subtraction instruction ESUB

Multiplication instruction EMVL

Division instruction EDIV

(3) Binary floating-point arithmetic instructions There are four floating-point arithmetic instructions: addition instruction EADD (FNC120), subtraction instruction ESUB (FNC121), multiplication instruction EMVL (FNC122) and division instruction EDIV (FNC123). The instructions for the four arithmetic instructions are shown in Figure 3. They all operate the floating-point numbers in the two source operands and send them to the target operand. When the divisor is 0, an operation error occurs and the instruction is not executed. This type of instruction only has 32-bit operations and occupies 13 program steps. The operation result affects the flags M8020 (zero flag), M8021 (borrow flag), and M8022 (carry flag). The source operand can be K, H, and D, and the target operand is D. If a constant is involved in the operation, it is automatically converted to a floating-point number.

Figure 3 Use of binary floating point arithmetic instructions

Binary floating-point operations also include instructions such as square root and trigonometric function operations, which are not explained here one by one.