Mitsubishi Electric FX3U SERIES - Page 274

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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
10 Arithmetic and Logical Operation ( + , − , × , ÷ ) – FNC 20 to FNC 29
10.1 FNC 20 – ADD / Addition
Program example
1. Difference between ADD instruction and INC instruction caused by a program for adding "+1"
When ADD[P] is executed, "1" is added to the contents of D0 every time X001 turns from OFF to ON.
ADD[P] instruction is similar to INCP instruction described later except the contents shown in the table below:
ADD, ADDP, DADD or DADDP
instruction
INC, INCP, DINC, DINCP instruction
Flag (zero, borrow or carry) Operates Does not operate
Operation result
16-bit
operation
+(+1)=
+32767→0→+1→+2→ +32767→−32768→−32767
+(−1)=
←−2←−1←0←−32768 ⎯
32-bit
operation
+(+1)=
+2,147,483,647→0→+1→+2→ +2,147,483,647→−2,147,483,648→−2,147,483,647
+(−1)=
←−2←−1←0←−2,147,483,648 ⎯
S D
S D
S D
S D
FNC 20
ADDP
D 0 K 1 D 0
X001
(D 0) + 1
→ (D 0)
FNC 24
INCP
D 0
X001
(D 0) + 1
→ (D 0)
S 1  S 2  D 