Mitsubishi Electric MELSEC FX3U Programming Manual page 238

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Caution
1. Using a label (P) number two or more times
In CALL instructions, a same number can be used two or more times in operands (P).
However, do not use a label (P) and number used in another instruction (CJ instruction).
X020
X030
Label
P 9
Program examples
1. Example of fundamental use (no nesting)
Label
P 10
2. Example of multiple CALL instructions in subroutines (multiple nesting)
CALL instruction can be used up to 4 times in subroutine programs. Nesting of up to five layers is allowed.
Label
P 11
Label
P 12
236
FNC 00
FNC 01
User program
X000
FNC 01
P 10
CALL
FNC 06
FEND
FNC 02
SRET
END
X001
FNC 01
P 11
CALLP
FNC 06
FEND
X002
FNC 01
P 12
CALL
FNC 02
SRET
X003
FNC 02
SRET
END
P 9
CJ
Bad
P 9
CALLP
Main program
While X000 is ON, the program execution jumps to a
step with the label P10.
Subroutine program
When SRET instruction is executed after the subroutine
program has executed, the program execution returns to
the original step +1.
Main program
When X001 turns ON from OFF, the program execution
jumps to the label P11 only once.
Subroutine program 1
When SRET instruction is executed, the program
execution returns to the main program.
If X002 is ON while the subroutine program 1 is
executed, the program execution jumps to a step with the
label P12.
Subroutine program 2
The subroutine program with P12 is executed, and then
the program execution returns to the subroutine program
with P11 by SRET instruction.
8 Program Flow – FNC 00 to FNC 09
8.2 FNC 01 – CALL / Call Subroutine