Mitsubishi Electric MELSEC FX3U - Functions and Operation Examples of Pointers for Branch

153
FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.12 Pointer [P and I]
1
Introduction
2
Overview
3
Instruction List
4
Devices in Detail
5
Specified the Device & Constant
6
Before Programming
7
Basic Instruction
8
FNC00-FNC09 Program Flow
9
FNC10-FNC19 Move & Compare
10
FNC20-FNC29 Arith. & Logic Operation
4.12.2 Functions and operation examples of pointers for branch
The roles and operations of pointers for branch are as described below.
Because all of these pointers are combined with applied instructions, refer to the explanation of each
instruction for the detailed method.
→ For details on interrupt function, refer to Chapter 36.
1. Applied instructions using pointers for branch (P)
• CJ (FNC 00) (conditional jump)
• CALL (FNC 01) call subroutine
• Role of pointer P63 for jump to the END step
P63 is a special pointer for jumping to the END step
when the CJ (FNC 00) instruction is executed.
Note that a program error will occur when P63 is
programmed as a label.
→ Refer to "5. Label unnecessary for the
pointer P63" in Section 8.1.
FNC 00
CJ
P 0
Jump
X001
Label
P0
When X001 turns ON, the PLC jumps to a label
position specified by CJ (FNC 00) instruction,
and executes the subsequent program.
FNC 01
CALL
P 1
Jump
X001
Label
P1
FNC 06
FEND
FNC 02
SRET
Main program
Subroutine
program
Return
When X001 turns ON, the PLC executes a
subroutine in the label position specified by
CALL (FNC 01) instruction, and then returns to
the original position by SRET (FNC 02)
instruction.
Label
P63
FNC 00
CJ
P 63
END
Should not be programmed.