2 FNC 01 – CALL / Call Subroutine

FX3S/FX3G/FX3GC/FX3U/FX3UC Series



8 Program Flow – FNC 00 to FNC 09



Programming Manual - Basic & Applied Instruction Edition



8.2 FNC 01 – CALL / Call Subroutine



1

Introduction



Caution

1. Using a label (P) number two or more times

In CALL instructions, the 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).

FNC 00

CJ



X030



FNC 01

CALLP



P9



2



P9



Overview



X020



Bad



3

User program



Instruction

List



Label

P9



1. Example of fundamental use (no nesting)



4



Program examples



FNC 01

CALL



Devices

in Detail



X000



P 10

Main program

While X000 is ON, the program execution jumps to a

step with the label P10.



FNC 06

FEND



5

Specified the

Device &

Constant



Label

P 10



Subroutine program

When SRET instruction is executed after the subroutine

program has executed, the program execution returns to

the original step +1.



FNC 02

SRET



6

Before

Programming



END



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.

FNC 01

CALLP



P 11



FNC 06

FEND

Label

P 11



Label

P 12



FNC 01

CALL

FNC 02

SRET



P 12



Main program

When X001 turns from OFF to ON, the program execution

jumps to the label P11 only once.



8



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.



FNC00-FNC09

Program Flow



X002



Basic

Instruction



X001



7



X003



FNC10-FNC19

Move & Compare



FNC 02

SRET



9



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.



END



10

FNC20-FNC29

Arith. & Logic

Operation



229



FX3S/FX3G/FX3GC/FX3U/FX3UC Series



8 Program Flow – FNC 00 to FNC 09



Programming Manual - Basic & Applied Instruction Edition



8.2 FNC 01 – CALL / Call Subroutine



8.2.1



Cautions on subroutines and interrupt routines

This section explains cautions on creating programs in subroutines and interrupt routines.

The explanation below is given for subroutines, but the situation also applies to interrupt routines.



1. When using timers in subroutines (or interrupt routines)

Use retentive type timers T192 to T199 in subroutines.

These timers execute counting when the coil instruction or END instruction is executed.

After a timer reaches the set value, the output contact is activated when the coil instruction or END instruction is

executed.

Because general timers execute counting only when the coil instruction is executed, they do not execute counting if

they are used in subroutines in which the coil instruction is executed only under some conditions.



2. When using retentive type 1 ms timers in subroutines (or interrupt routines)

If a retentive type 1 ms timer is used in a subroutine, note that the output contact is activated when the first coil

instruction (or subroutine) is executed after the timer reaches its set value.



3. Countermeasures against latches of devices used in subroutines (or interrupt routines)

Devices which were set to ON in a subroutine are latched in the ON status even after the subroutine is finished. (Refer

to the program example shown below.)

When RST instruction for a timer or counter is executed, the reset status of the timer or counter is latched also.

For turning OFF such a device latched in the ON status or for canceling such a timer or counter latched in the reset

status, reset such a device in the main program after the subroutine is finished, or program a sequence for resetting

such a device or for deactivating RST instruction in the subroutine.

(Refer to the program example shown on the next page.)

Example in which outputs are latched

In the following program example, the counter C0 is provided to count X001. When X000 is input, the subroutine P0 is

executed only in one scan, and then the counter is reset and Y007 is output.

1)



Program example

X000



FNC 01

CALLP



X001



C0



P0



K10



FNC 06

FEND

P0



X000



RST



C0



Y007

FNC 02

SRET



2)



Timing chart

Execution of

subroutine P0

triggered by X000



Subroutine is executed.



X001



Current

value of C0



1



2



3



Counter

is reset.



Because the reset instruction

for C0 is valid, the current value

of C0 remains unchanged even

if pulses are input.



RST

C0



Remains reset.



Y007



Y007 is being output.

Outputs are held.



230



FX3S/FX3G/FX3GC/FX3U/FX3UC Series



8 Program Flow – FNC 00 to FNC 09



Programming Manual - Basic & Applied Instruction Edition



8.2 FNC 01 – CALL / Call Subroutine



1

1)



Introduction



Example for resetting held outputs (countermeasures)

Program example

X000



FNC 01

CALLP



X001

X002



2



K10



RST



Y007



Overview



C0



P0



Y007 is reset at an arbitrary timing.



FNC 06

FEND

X000



RST



C0



RST



C0



Instruction

List



P0



3

A



B



M8001



4



The preceding RST C0 instruction is

deactivated in the subroutine.



Devices

in Detail



RUN monitor

(normally OFF)



Y007

FNC 02

SRET



5



Timing chart



Specified the

Device &

Constant



2)



Subroutine is

executed.



Execution of P0 is

triggered by X000



6



X001



RST

C0



1



3



2



1



Counter is reset (part

A in above program).



2



3



Before

Programming



Current

value of C0



4



Counter reset instruction is deactivated

(part B in above program).



7

Basic

Instruction



Y007

X002



Y007 is reset.



8

FNC00-FNC09

Program Flow



9

FNC10-FNC19

Move & Compare



10

FNC20-FNC29

Arith. & Logic

Operation



231



FX3S/FX3G/FX3GC/FX3U/FX3UC Series



8 Program Flow – FNC 00 to FNC 09



Programming Manual - Basic & Applied Instruction Edition



8.3



8.3 FNC 02 – SRET / Subroutine Return



FNC 02 – SRET / Subroutine Return



Outline

This instruction returns the program execution from a subroutine to the main program.



1. Instruction format



FNC 02

SRET



Independent Inst. Mnemonic



1 step SRET



Operation Condition

Continuous

Operation



This instruction is the independent type, and

does not require drive contact.



2. Set data

Operand type

–



Description



Data type



There is no set data.



–



3. Applicable devices

Operand

Type



Bit Devices

System User



Word Devices

Digit Specification



System User



X Y M T C S D .b KnX KnY KnM KnS T



–



Others

Special

Unit



C D R U \G



Index

V



Constant



Z Modify K



H



Real

CharacPointer

Number ter String

E



" "



P



There are no applicable devices.



Explanation of function and operation

When CALL instruction in the main program is executed, the program execution jumps to a subroutine.

SRET instruction returns the program execution to the main routine.

→ Refer to Section 8.2.



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FX3S/FX3G/FX3GC/FX3U/FX3UC Series



8 Program Flow – FNC 00 to FNC 09



Programming Manual - Basic & Applied Instruction Edition



1



FNC 03 – IRET / Interrupt Return



Introduction



8.4



8.4 FNC 03 – IRET / Interrupt Return



2



Outline



Overview



This instruction returns the program execution from an interrupt routine to the main program.



1. Instruction format



FNC 03

IRET



Independent Inst. Mnemonic



1 step IRET



Operation Condition



3



This instruction is the independent type, and

does not require drive contact.



Continuous

Operation



Instruction

List



2. Set data

Operand type

–



Description



Data type



There is no set data.



–



4



Operand

Type



Bit Devices



Word Devices



System User



Digit Specification



System User



X Y M T C S D .b KnX KnY KnM KnS T



–



Others

Special

Unit



C D R U \G



Index

V



Constant



Z Modify K



H



Real

CharacPointer

Number ter String

E



" "



P



There are no applicable devices.



When an interrupt (input, timer or counter) is generated while the main program is executed, the program execution

jumps to an interrupt (I) routine.

IRET instruction returns the program execution to the main routine.

The table below shows three types of jump to an interrupt routine.



Function



Interrupt No.



Description



Reference



I00* to I50*



Timer interrupt



I6** to I8**



Executes the interrupt processing at a specified time interval (constant

cycle).



Section 36.5



Counter interrupt*1



I010 to I060



Executes the interrupt processing when a high-speed counter reaches

it’s set value.



Section 36.6



*1.



This function is supported only in FX3U/FX3UC PLCs.



7

Basic

Instruction



Input interrupt



Executes the interrupt processing when an input (X) signal turns ON or Section 36.3 and

OFF.

Section 36.4



6

Before

Programming



1. Types of interrupt function



5

Specified the

Device &

Constant



Explanation of function and operation



Devices

in Detail



3. Applicable devices



→ For the interrupt function, refer to Chapter 36.



8

FNC00-FNC09

Program Flow



9

FNC10-FNC19

Move & Compare



10

FNC20-FNC29

Arith. & Logic

Operation



233