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Omron IPC Machine Controller Industrial Panel PC / Industrial Box PC. Software User’s Manual (Industrial PC Platform NY-series) - page 6

5 Designing Tasks

5-5

Assignment and Settings Related to

Tasks

This section describes the assignment and setting related to tasks.

5-5-1

Assigning I/O Refreshing to Tasks

I/O refreshing of the EtherCAT slaves is assigned to the tasks. Unit of assignment is different depend-

ing on the target for I/O refreshing. Unit of assignment refers to a target or a group of targets for I/O

refreshing assigned to one task. For example, when the unit of assignment is Slave Terminal, you can

assign I/O refreshing to only one task even if more than one NX Unit is connected to a Communications

Coupler Unit.

If you want to perform input and output operations in tasks to which I/O refreshing is not assigned, refer

to Input and Output Operations in Tasks to Which I/O Refreshing Is Not Assigned on page 5-34.

The following table shows the relationship among the target for I/O refreshing, the assignable task, and

the unit of assignment.

I/O refreshing target

Assignable task

Unit of assignment

Communications Coupler Unit

Primary periodic task

Slave Terminal

5

EtherCAT slaves

Primary periodic task

Slave

Sysmac Studio Setting Procedure

For the slaves and Units that are not assigned to axes, set the tasks in which to perform I/O refreshing

in I/O Control Task Settings under Configuration and Setup - Task Settings on the Sysmac Studio.

Refer to I/O Control Task Settings on page 4-9 for details.

For the slaves and Units that are assigned to axes, specify the motion controls to use in Motion Con-

trol Setup under Configurations and Setup on the Sysmac Studio. The tasks to perform I/O refresh-

ing are set.

Refer to the NY-series Industrial Panel PC / Industrial Box PC Motion Control User's Manual (Cat. No.

W559) for details.

Timing of I/O Refreshing

The table below shows when I/O is refreshed for EtherCAT slaves.

I/O refreshing target

I/O control task

Period of I/O refreshing

EtherCAT slaves

Primary periodic task

Task period of the primary periodic task

Accessing I/O from the User Program

You use device variables to access I/O ports from the user program.

Access the device variables from a program in the task that is set in the I/O Control Task Settings.

5-33

5 Designing Tasks

Input and Output Operations in Tasks to Which I/O Refreshing Is Not

Assigned

If you attempt to output data directly from a task to which I/O refreshing is not assigned, an error will

occur when you check the program on the Sysmac Studio. For example, if the processes for NX Units

are assigned to different tasks on the Slave Terminal, data can be output only from the task to which I/O

refreshing is assigned. In this case, you need to create the program to pass the data from the task to

which I/O refreshing is not assigned to the task to which I/O refreshing is assigned and output data from

the task to which I/O refreshing is assigned.

The following sample programming shows how to pass the data from the task to which I/O refreshing is

not assigned to the task to which I/O refreshing is assigned and output data from the task to which I/O

refreshing is assigned.

In this sample programming, the external data input processing is performed in a task to which I/O

refreshing is not assigned. Usually, this kind of processing causes a warning to occur when you check

the program on the Sysmac Studio. However, the execution of processing is possible.

z Unit Configuration

A Slave Terminal is used. The following table shows the Unit configuration of the Slave Terminal.

Model number

Product name

NX-ECC20

EtherCAT Coupler Unit

NX-ID3317

DC Input Unit

NX-OD3256

Transistor Output Unit

z I/O Map

The following I/O map is used. The table below shows the bits that are used in the sample program-

ming.

Data

Variable com-

Position

Port

Description

R/W

Variable

Variable type

type

ment

Unit1

NX-ID3317

Input Bit 00

Input bit 00

R

BOOL

ComIn

Common input

Global variable

value

Unit2

NX-OD3256

Output Bit 00

Output bit 00

W

BOOL

OutA1

Output value A1

Global variable

Output Bit 01

Output bit 01

W

BOOL

OutA2

Output value A2

Global variable

Output Bit 02

Output bit 02

W

BOOL

OutB1

Output value B1

Global variable

Output Bit 03

Output bit 03

W

BOOL

OutB2

Output value B2

Global variable

5-34

5 Designing Tasks

z

I/O Specifications

The I/O specifications are as follows:

• OutA1 changes from FALSE to TRUE one second after the value of ComIn changes from FALSE

to TRUE. In the same way, OutA2 changes to TRUE two seconds, OutB1 three seconds and

OutB2 four seconds after the value of ComIn changes to TRUE.

• When the value of ComIn changes from TRUE to FALSE, the values of OutA1, OutA2, OutB1 and

OutB2 change from TRUE to FALSE.

The following figure shows the timing chart.

TRUE

ComIn

FALSE

1s

TRUE

OutA1

FALSE

2s

TRUE

OutA2

FALSE

3s

TRUE

OutB1

FALSE

4s

TRUE

OutB2

FALSE

z

Task Processing

5

The primary periodic task and priority-16 periodic task are used. The I/O refreshing is assigned to

the primary periodic task.

OutA1 and OutA2 are controlled in the primary periodic task. A series of processing, i.e., input of

ComIn, calculations and outputs of OutA1 and OutA2, is performed in the primary periodic task.

For controls of OutB1 and OutB2, the processing from input of ComIn to calculations is performed in

the periodic task. The calculation results of the periodic task are assigned to the temporary global

variables tmp_OutB1 and tmp_OutB2. In the primary periodic task, the values of tmp_OutB1 and

tmp_OutB2 are assigned to OutB1 and OutB2. Then, OutB1 and OutB2 are output.

The Controller may pause the periodic task in order to execute the primary periodic task. The

assignment of calculation results to tmp_OutB1 and tmp_OutB2 may be performed before or after

the pause of the periodic task. And the timing of assignment determines the timing of output of cal-

culation results in the primary periodic task.

5-35

5 Designing Tasks

The following figure shows an example of processing flow. The task period of the periodic task is set

to twice as long as that of the primary periodic task.

Task period

Primary

IOUPG

IO

UPG

IO

UPG

IO

UPG

periodic task

(1)

(2)

(5)

(6)

(8)

(9)

(10)

Task period

Priority-16

Pausing

Pausing

periodic task

(3)

(4)

(7)

If the values are assigned to tmp_OutB1

If the values are assigned to tmp_OutB1

and tmp_OutB2 in step (4), they are

and tmp_OutB2 in step (7), they are

output in step (8).

output in step (10).

(1)

ComIn is input during I/O refreshing in the primary periodic task.

(2)

The calculation is performed during the user program execution in the primary peri-

odic task and the values are assigned to OutA1 and OutA2.

Also, the values of tmp_OutB1 and tmp_OutB2 are assigned to OutB1 and OutB2.

However, the values of tmp_OutB1 and tmp_OutB2 are the initial values because the

values are not assigned to tmp_OutB1 and tmp_OutB2 in the periodic task. There-

fore, the values of OutB1 and OutB2 are also the initial values.

(3)

ComIn is input in the periodic task.

(4)

The calculation is performed during the user program execution in the periodic task.

If the primary periodic task is executed while the periodic task execution is in prog-

ress, the periodic task is paused. Depending on the timing of processing in the peri-

odic task, the assignment of the values to tmp_OutB1 and tmp_OutB2 may be

performed before or after the pause of the periodic task.

(5)

OutA1, OutA2, OutB1 and OutB2 are output during I/O refreshing in the primary peri-

odic task.

Also, ComIn is input again.

(6)

The calculation is performed during the user program execution in the primary peri-

odic task and the values are assigned to OutA1 and OutA2.

Also, the values of tmp_OutB1 and tmp_OutB2 are assigned to OutB1 and OutB2. If

the values are assigned to tmp_OutB1 and tmp_OutB2 in step (4), the calculation

results of the periodic task are reflected in OutB1 and OutB2. If the values are not

assigned to tmp_OutB1 and tmp_OutB2 in step (4), the values of tmp_OutB1 and

tmp_OutB2 are the initial values. Therefore, the values of OutB1 and OutB2 are also

the initial values.

(7)

The calculation is performed during the user program execution in the periodic task

that follows step (4).

If the values are not assigned to tmp_OutB1 and tmp_OutB2 in step (4), they are

assigned here.

(8)

OutA1, OutA2, OutB1 and OutB2 are output during I/O refreshing in the primary peri-

odic task.

If the values are assigned to tmp_OutB1 and tmp_OutB2 in step (4), the calculation

results of the periodic task are output as OutB1 and OutB2.

If the values are assigned to tmp_OutB1 and tmp_OutB2 in step (7), the initial values

of OutB1 and OutB2 are output.

5-36

5 Designing Tasks

(9) The calculation is performed during the user program execution in the primary peri-

odic task and the values are assigned to OutA1 and OutA2.

Also, the values of tmp_OutB1 and tmp_OutB2 are assigned to OutB1 and OutB2. If

the values are assigned to tmp_OutB1 and tmp_OutB2 in step (7), the calculation

results of the periodic task are reflected in OutB1 and OutB2.

(10) OutA1, OutA2, OutB1 and OutB2 are output during I/O refreshing in the primary peri-

odic task.

If the values are assigned to tmp_OutB1 and tmp_OutB2 in step (7), the calculation

results of the periodic task are output as OutB1 and OutB2.

You can use the Lock and Unlock instructions to perform the task exclusive controls to prevent the

values of tmp_OutB1 and tmp_OutB2 from being overwritten by the periodic task before they are

accessed by the primary periodic task. Refer to 5-6-1 Ensuring Concurrency of Variable Values

between Tasks for details on task exclusive controls.

z

Global Variable Table

The global variables are shown below.

Global variable table

Initial

Name

Data type

AT specification

Comment

value

ComIn

BOOL

FALSE

ECAT://node#[1,1]/Input Bit 00

Common input value

OutA1

BOOL

FALSE

ECAT://node#[1,2]/Output Bit 00

Output value A1

5

OutA2

BOOL

FALSE

ECAT://node#[1,2]/Output Bit 01

Output value A2

OutB1

BOOL

FALSE

ECAT://node#[1,2]/Output Bit 02

Output value B1

OutB2

BOOL

FALSE

ECAT://node#[1,2]/Output Bit 03

Output value B2

tmp_OutB1

BOOL

FALSE

Temporary variable for B1

tmp_OutB2

BOOL

FALSE

Temporary variable for B2

z

Ladder Diagram for Primary Periodic Task

The ladder diagram for the primary periodic task is shown below.

Internal variable table

Name

Data type

A1_Wait

TON

A2_Wait

TON

External variable table

Name

Data type

Comment

ComIn

BOOL

Common input value

OutA1

BOOL

Output value A1

OutA2

BOOL

Output value A2

OutB1

BOOL

Output value B1

OutB2

BOOL

Output value B2

tmp_OutB1

BOOL

Temporary variable for B1

tmp_OutB2

BOOL

Temporary variable for B2

5-37

5 Designing Tasks

Algorithm

Input of ComIn, calculations and outputs and output of OutA1 and OutA2

A1_Wait

ComIn

OutA1

TON

In

Q

T#1s

PT ET

A2_Wait

OutA2

TON

In

Q

T#2s

PT ET

Assignment of the values tmp_OutB1 and tmp_OutB2 to OutB1 and OutB2, and output of OutB1 and OutB2

P_On

Lock

En ENO

USINT#1

Index

tmp_OutB1

OutB1

tmp_OutB2

OutB2

Unlock

En ENO

USINT#1

Index

z

Ladder Diagram for Periodic Task

The ladder diagram for the periodic task is shown below.

Internal variable table

Name

Data type

B1_Wait

TON

B2_Wait

TON

External variable table

Name

Data type

Comment

ComIn

BOOL

Common input value

tmp_OutB1

BOOL

Temporary variable for B1

tmp_OutB2

BOOL

Temporary variable for B2

5-38

5 Designing Tasks

Algorithm for periodic task

Input of ComIn and calculations of tmp_OutB1 and tmp_OutB2

P_On

Lock

En ENO

USINT#1

Index

ComIn

B1_Wait

TON

tmp_OutB1

In

Q

T#3s

PT ET

B2_Wait

TON

tmp_OutB2

In

Q

T#4s

PT ET

Unlock

En ENO

USINT#1

Index

5

5-5-2

Assigning Tasks to Programs

You assign the programs to execute to tasks. (You can assign up to 128 programs to one task.) Also,

you set the operation of the programs at the start of operation.

Order of Program Execution

The order of execution of the programs in a task is set with the Sysmac Studio.

Initial Status for Programs at the Start of Operation

Set the operation of the programs at the start of operation. The Initial Status at the start of operation is

used to set whether to execute the program when the task to which the program is assigned is exe-

cuted for the first time after the operating mode of the Controller is changed from PROGRAM mode to

RUN mode. You have a setting option between Run or Stop.

If the Initial Status is Stop, when enabling the execution of the specified program with the PrgStart

instruction, it is executed from the next time the timing for executing the program occurs. If the Initial

Status is Run, when disabling the execution of the specified program with the PrgStop instruction, it is

disabled from the next time the timing for executing the program occurs.

z Sysmac Studio Setting Procedure

Assign programs to tasks, set the order of program execution within the task, and set the Initial Sta-

tus for each program in Program Assignment Settings under Configurations and Setup - Task

Settings on the Sysmac Studio. Refer to Program Assignment Settings on page 4-9 for details.

5-39

5 Designing Tasks

POUs That You Can Assign to Tasks

From 0 to 128 programs can be assigned to one task.

You can assign only program POUs. You cannot assign function block instances or functions directly to

tasks. You cannot assign the same program to more than one task.

5-5-3

Parameters for Primary Periodic Task and Periodic Tasks

The parameters for primary periodic task and periodic tasks are given below.

z Parameters for Primary Periodic Tasks

Changes

Update

Parameter

Setting range

Default

in RUN

timing

mode

Task Type

Specify the primary periodic task.

---

When

Not

down-

allowed.

Execution priority

Always 4.

---

loaded to

Task Name

Text string

Primary-

Controller

Task

Period/

Task period*1

500 μs to 8 ms (in 250-μs increments)

1 ms

Execu-

tion Con-

ditions

Task Period Exceeded Detec-

Specify whether to detect an error if

Detect.

tion

the task execution time exceeds the

specified task period.

• Detect (a minor fault level Controller

error occurred).

• Do not detect (an observation is

recorded in event log).

Refer to Task Period Exceeded on

page 5-53 for details.

Task Timeout Detection Time

Set the time to detect a timeout if task

5

execution does not end, e.g., if there is

an infinite loop.

Set a multiple of the task period.

1 to 5

Refer to Task Execution Timeout on

page 5-54 for details.

Variable Access Time [%]

Set the percentage of the task period

3%

to assign to variable access.

1% to 50%

Refer to Settings for Variable Access

Time on page 5-51 for details.

*1

The process data communications cycle (process data communications cycle) in the EtherCAT settings will

be the same as this period.

5-40

5 Designing Tasks

z Parameters for Priority-16, Priority-17, and Priority-18 Periodic Tasks

Changes

Update

Parameter

Setting range

Default

in RUN

timing

mode

Task Type

You can set any of the following.

---

When

Not

down-

allowed.

Priority-16 periodic task

loaded to

Priority-17 periodic task

Controller

Priority-18 periodic task

Execution

Automatically set to 16, 17, or 18.

---

priority

Task Name

Text string

Periodic

Task0

Period/

Task period

Refer to 5-3-1 Specifications of Tasks for

10 ms

Execution

NY-series Controllers.

Conditions

Task Period Exceeded

The same as for the primary periodic task.

The same

Detection

as for the

primary

Task Timeout Detection

periodic

Time

task.

Variable Access Time [%]

5

z Event Task Parameters

Changes

Update

Parameter

Setting range

Default

in RUN

timing

mode

Task Type

You can set any of the following.

---

When

Not

Priority-8 event task

down-

allowed.

Priority-48 event task

loaded to

Controller

Task Name

Text string

EventTask0

Execution Condition

Select either Execution by instruction or

Execution

When a variable expression is satisfied.

with an

instruction

Task Timeout Detection

Set the time to detect a timeout if task exe-

• Execu-

Time

cution does not end, e.g., if there is an

tion prior-

infinite loop. The setting unit is millisec-

ity of 8:

onds.

200 ms

• Execution priority of 8: 1 to 500 ms

• Execu-

tion prior-

• Execution priority of 48: 1 ms to 10 s

ity of 48:

1 s

z Sysmac Studio Setting Procedure

Add and set the tasks in the Task Settings under Configurations and Setup on the Sysmac Stu-

dio.

Refer to Task Settings on page 4-7 for details.

5-41

5 Designing Tasks

5-6

Ensuring Concurrency of Variable

Values

This section describes how to ensure concurrency of variable values between tasks and provides an

overview of variable access from outside the Controller.

5-6-1

Ensuring Concurrency of Variable Values between Tasks

If more than one task reads or writes the same global variable, you can use either of the following two

methods to ensure the concurrency of the value of the global variable between the tasks. These are

collectively called the exclusive control of variables in tasks.

Method 1: Write the global variable from only one task and read the variable from the other tasks.

Use the settings for exclusive control of variables in tasks.

Method 2: Write the global variable from more than one task.

Use the task exclusive control instructions.

Method 1: Settings for Exclusive Control of Variables in Tasks

z

Introduction

You can specify the task that refreshes a global variable and the tasks that access the global vari-

able. This ensures the concurrency of the value of the global variable from the point of view of the

tasks that access the variable.

A single task is set to read and write the value of a specified global variable. That task is called the

refreshing task. Tasks that only read the value of the global variable are also specified. These tasks

are called accessing tasks. This ensures the concurrency of the value of the global variable.

Accessing

Read only

task: Task B

Read/write

Refreshing

Global variable

task: Task A

Refreshing task is specified.

Refreshing task: Task A

Accessing

Read only

task: Task C

z

Application Example

The refreshing task specification is used to ensure the concurrency of the value of a global variable

within a periodic task when the variable is written in the primary periodic task.

Refreshing task

Accessing task

Program

Program

Read/write

Read only

External variable GVar1

Global variable GVar1

External variable GVar1

The most recent value of the

variable at the end of refreshing

task execution is read at the start

of accessing task execution.

5-42

5 Designing Tasks

z System

If a refreshing task is set for a global variable, the accessing task, at the start of accessing task exe-

cution, always reads the most recent value of the variable that was written at the completion of

refreshing task execution.

Task period of task A

Task period of task A

Task period of task A

Refreshing

Refreshing

Refreshing

task: Task A

task: Task A

task: Task A

Write

Write

Write

Global variable

Value of

Global variable

Value of variable

Global variable

Value of variable

variable is read.

is not read.

is not read.

Accessing task:

Accessing task:

Accessing task:

Task B

Task B

Task B

Task period of task B

This will allow you to maintain the concurrency of the values of global variables within the tasks with-

out performing any special programming.

If an instruction that writes the value to a global variable is used in the accessing task, an error will

5

occur when you check the program on the Sysmac Studio.

5-43

5 Designing Tasks

Precautions for Correct Use

If you are using the ActEventTask instruction between two tasks, you must keep in mind when

the global variables are accessed, and when they are refreshed. For example, in the following

diagram, the value of the GVarA global variable that is accessed from the event task is the value

that was current at the end of task period 1. Therefore, even if the periodic task in task period 2

writes the value of GVarA, that value will not be reflected in the event task. The value that the

event task writes to the GVarB global variable is not passed to the periodic task until the start of

task period 3. Even if the periodic task in task period 2 accesses the value of GVarB, the value

that the event task writes will not be accessed.

Execution

Event task

priority

(refreshing task)

High

A value of 123

A value of 654

is read.

is written.

GVarA

GVarB

The value of GVarA is passed

The value of GVarB is passed to

123

654

to the event task at this point.

the periodic task at this point.

Task period 1

Task period 2

Task period 3

Execution of

ActEventTask

Periodic task

Periodic task

Periodic task

(accessing task)

(accessing task)

(accessing task)

A value of

123 is

written.

A value of 987

A value of 567

A value of

A value of 654 is read.

Low

is written.

987 is read.

is written.

GVarA

GVarB

GVarA

GVarB

GVarB

123

987

567

987

654

The value that is written

The value that the event task

here is not reflected in

writes cannot be accessed.

the event task.

Because of this, do not use exclusive control of variables in tasks to pass the values of global

variables if you are using the ActEventTask instruction to execute event tasks. To ensure the

concurrency of global variables when using the ActEventTask instruction, you should use the

Task_IsActive (Determine Task Status) instruction. The Task_IsActive instruction determines

whether the specified task is in execution or waiting to be executed. Use this instruction to pre-

vent other tasks from accessing variables that the event task writes to while it is in execution.

Refer to the NY-series Instructions Reference Manual (Cat. No. W560) for details on the Task_I-

sActive instruction.

z

Restrictions

• Only one refreshing task can be set for each global variable. If it is necessary to write a global

variable from more than one task, use the task exclusive control instructions described below to

ensure concurrency.

• If you specify a refreshing task for a structure or union variable, you must specify only one refresh-

ing task for the entire structure or union variable. You cannot specify a different refreshing task for

different structure or union members.

• If you specify a refreshing task for an array variable, you must specify only one refreshing task for

the entire array variable. You cannot specify a different refreshing task for different array ele-

ments.

5-44

5 Designing Tasks

Precautions for Correct Use

Do not write the value of a variable for which concurrency is required from any task that is not the

refreshing task, e.g., do not write the value from the accessing task. If you read or write the value

of a variable for which a refreshing task is set from any task that is not a refreshing or accessing

task, the concurrency of the global variable may be lost. If you write such a program, a warning is

given when the program is checked.

Additional Information

You can use a data trace to sample an external variable for a global variable for which settings

for exclusive control of variables in tasks are used. This allows you to sample the values of the

global variable in the refreshing and accessing tasks in a data trace. Refer to 8-4-4 Data Tracing

for information on data tracing.

z Sysmac Studio Setting Procedure

Set the global variables for which to specify refreshing tasks, and set the accessing tasks in Settings

for Exclusive Control of Variables in Tasks under Configurations and Setup - Task Settings

on the Sysmac Studio.

Refer to Settings for Exclusive Control of Variables in Tasks on page 4-10 for details.

5

5-45

5 Designing Tasks

Method 2: Task Exclusive Control Instructions

Use the task exclusive control instructions (i.e., the Lock and Unlock instructions) when it is necessary

to write the value of a global variable from more than one task while maintaining concurrency in the

value of the variable.

The task exclusive control instructions create a lock region from one Lock instruction to the next Unlock

instruction. If a lock region in one task is being executed, the lock regions with the same lock number in

other tasks are not executed. If you place the instructions that write to the global variable in lock

regions, the concurrency of the value is maintained even if you write the value of the variable from more

than one task.

Refer to information on the Lock and Unlock instructions in the NY-series Instructions Reference Man-

ual (Cat. No. W560) for details.

Example:

In this example, task A and task B both have lock region 1. The priority of task B is higher than the pri-

ority of task A.

If the execution condition for task B is met during execution of lock region 1 in task A, execution of task

A is paused during lock region 1 and task B is executed. However, in this case, lock region 1 in task A is

not completed, so task B is paused before it processes lock region 1. When task B is paused, execution

of lock region 1 in task A is started again.

Task A

Program

Executed.

Lock instruction

Global variable

Refreshed.

Higher priority

Task B

Lock region 1

Executed.

Executed.

Program

Unlock instruction

Lock instruction

Execution is not

started until

execution of region

Lock region 1

1 in task A is

completed.

Unlock instruction

5-46

5 Designing Tasks

When execution of lock region 1 in task A is completed, task A is paused again and the remainder of

lock region 1 in task B is executed. The concurrency of the value of the global variable is maintained by

implementing exclusive control of the write processing of the global variable between the tasks.

Task A

Program

Lock instruction

Task B

Lock region 1

Program

Lock instruction

Unlock instruction

Executed.

Lock region 1

Refreshed.

Global variable

Unlock instruction

Precautions for Correct Use

• Do not make the locked regions any longer than necessary. If the lock regions are too long,

the task execution period may be exceeded.

5

• Always use the Lock and Unlock instructions together as a set in the same section of the same

POU.

Example of Accessing the Same Global Variable between Tasks

This section describes how to request processing to another task with multiple global variables.

The following sample programming uses one global variable gReq as an exclusive flag for processing

to perform exclusive control in the user program. Even in this case, exclusive control of variables in

tasks is required for the access logic to the gPar1, gPar2, and gReq global variables that are used

between tasks.

A sample programming that uses the task exclusive control instructions (i.e., the Lock and Unlock

instructions) to perform exclusive control is shown.

z Global Variables

Name

Data type

Comment

gReq

BOOL

Request flag

gPar1

ULINT

Parameter 1

gPar2

DATA_AND_TIME

Parameter 2

5-47

5 Designing Tasks

z

Task That Makes Processing Requests (MainTask)

• Internal Variables

Name

Data type

Comment

ReqTrg

BOOL

Request trigger

cCnt

ULINT

100-ms counter value

cTime

DATA_AND_TIME

Current time

• ST Program

cCnt:=Get100msCnt();

(* Get the 100-ms counter value. *)

cTime:=GetTime();

(* Get the current time. *)

Lock(1);

(* Start an exclusive lock between tasks. *)

IF ReqTrg=TRUE AND gReq=FALSE THEN

(* Access the exclusive flag. *)

gPar1:=cCnt;

(* Set the parameter to process in SubTask. *)

gPar2:=cTime;

(* Set the parameter to process in SubTask. *)

gReq:=TRUE;

ReqTrg:=FALSE;

END_IF;

Unlock(1); (* Stop an exclusive lock between tasks. *)

z

Task That Receives Processing Requests (SubTask)

• Internal Variables

Name

Data type

Comment

ReqBusy

BOOL

---

UserDefFB_ins

UserDefFB

User-defined function block instance that exe-

cutes processing

• ST Program

Lock(1);

(* Start an exclusive lock between tasks. *)

IF ReqTrg=TRUE AND gReq=FALSE THEN

(* Access the exclusive flag. *)

ReqBusy:=TRUE;

UserDefFB_ins.PutData:=gPar1;

(* Read the parameter from MainTask. *)

UserDefFB_ins.PutData:=gPar2;

(* Read the parameter from MainTask. *)

gReq:=FALSE;

(* Reset the exclusive flag. *)

UserDefFB_ins.Execute:=TRUE;

END_IF;

Unlock(1);

(* Stop an exclusive lock between tasks. *)

UserDefFB_ins();

IF UserDefFB_ins.Done:=TRUE THEN

UserDefFB_ins.Execute:=FALSE;

ReqBusy:=FALSE;

END_IF;

5-48

5 Designing Tasks

5-6-2

Variable Access from Outside the Controller

A variable access from outside the Controller is executed during the system service. The system ser-

vice has a lower execution priority than tasks. This means, if multiple variables are accessed from out-

side the Controller, refreshing all variable values may not be completed in a task period. If refreshed

variables and not-refreshed variables are mixed in the user program, the Controller may perform unin-

tended operation.

To avoid this, make the variable access from outside the Controller be executed during the system

common processing 2 of the task. By making this, multiple variable values can be securely refreshed in

the same task period.

z Accessing Variables from Outside the Controller during the System Service

The access to multiple variables may not be completed in the same task period.

Primary period

Primary period

Primary

IO

UPG

MC

IO

UPG

MC

periodic task

System common

processing 1

System

System common

SS

services

processing 2

5

Variable access 1 from

Variable access 2 from

outside the Controller

outside the Controller

z Accessing Variables from Outside the Controller during the System Common

Processing 2

The access to multiple variables is securely executed in the same task period.

Primary period

Primary period

Primary

IO

UPG

MC

IO

UPG

MC

periodic task

System common

processing 1

System

System common

services

processing 2

Variable access 1 from

Variable access 2 from

outside the Controller

outside the Controller

5-49

5 Designing Tasks

This section particularly describes how to execute the variable access from outside the Controller

during the system common processing 2 of the task.

Methods to Access Variables From Outside the Controller

There are the following four methods to access variables from outside the Controller.

• Sysmac Studio

• NA/NS-series PT

• EtherNet/IP tag data links

• CIP communications instruction from the host computer

If the Sysmac Studio is used to access variables, it can only refresh the variable values during the sys-

tem common processing 2 of the task. Values are accessed during the system services.

Tasks that Execute Variable Access during the System Common

Processing 2

The tasks that execute variable access from outside the Controller during the system common process-

ing 2 are predetermined as follows according to the variable types.

Variable

Task that update values

Global variables specified in the settings for exclu-

The refreshing task specified in Settings for Exclusive

sive control of variables in tasks

Control of Variable in Tasks under Configurations

and Setup - Task Settings on the Sysmac Studio.

Device variables for EtherCAT slaves

Tasks specified in I/O Control Task Settings under Con-

figurations and Setup - Task Settings on the Sysmac

Studio.

Settings for Executing Variable Access during the System Common

Processing 2

To access variables from outside the Controller during the system common processing 2, it is neces-

sary to make the following two settings on the Sysmac Studio.

• Settings for exclusive control of variables in tasks (when the target variables are the global variables)

• Settings for variable access time

Settings for Exclusive Control of Variables in Tasks

If global variables are accessed from outside the Controller during the system common processing 2 of

the task, it is necessary to make setting for exclusive control of variables in tasks. The exclusive control

of variables in tasks refers to the function that specifies the task that can refresh the target global vari-

able. This function prevents the target variable from being updated by other tasks or by other methods

to access variables from outside the Controller.

Refer to Settings for Exclusive Control of Variables in Tasks on page 4-10 for the details on the exclu-

sive control of variables in tasks.

Precautions for Correct Use

When you use EtherNet/IP tag data links, always specify the same task as the refreshing task for

all tags (variables that have Network Publish attribute) in the same tag set. Otherwise, multiple

tags in a tag set may be refreshed in separate task periods.

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5 Designing Tasks

Settings for Variable Access Time

When variable access from outside the Controller is executed during the system common processing 2

of the task, the task execution time may be longer. The user must set the upper limit of the processing

time for accessing variables on the Sysmac Studio. The variable access time refers to the upper limit of

the processing time for accessing variables.

z

Calculating Variable Access Time

Use the following equation for calculating the variable access time.

Variable access time [μs] = total size of variables [bytes] * a + number of variables * b + number of

accesses * c + d

The values of the constants a to d in above equation are given in the following table for the NY-

series Controller.

Controller model

Constant value [μs]

number

a

b

c

d

NY52-

0.0006

0.100

1.40

6.60

z

Setting Variable Access Time

Set the variable access time in the Configurations and Setup − Task Settings on the Sysmac Stu-

5

dio. The setting must be made for each task by entering the ratio to the task period. The default

value is 3%. For the details on the settings, refer to the Sysmac Studio Version 1 Operation Manual

(Cat. No. W504).

z

Example of Variable Access Time Setting

The following is an example of variable access time setting.

In this example, it is assumed that there are the following three variable accesses from outside the

Controller to the task that operates in the NY52-.

Total size of vari-

Number of vari-

Number of

Access No.

Source of variable access

ables to access

ables to access

accesses

[bytes]

1

EtherNet/IP tag data link

600

8

1

2

EtherNet/IP tag data link

200

4

1

3

CIP communications instruction

1,000

1

1

Using the equation, the variable access time for Access No.1 is calculated as follows.

Variable access time for Access No.1 = 600 * 0.0006 + 8 * 0.100 + 1 * 1.40 + 6.60

= 9.16 [μs]

In the same way, you can calculate the access time for the other accesses and get the following val-

ues.

Access No.

Variable Access Time [μs]

1

9.16

2

8.52

3

8.7

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5 Designing Tasks

If only one of these accesses occurs in one task period, you set the variable access time to the one

for Access No.1, which requires the longest access time.

The variable access time for Access No.1 is 9.16 μs. Therefore, when the task period is 500 μs, the

variable access time is set to 9.16/500 ≈ 2%.

If every access occurs once in one task period, the variable access time is calculated with the equa-

tion as follows.

Variable access time = (600 + 200 + 1000) * 0.0006 + (8 + 4 + 1) * 0.100 + (1 + 1 + 1) * 1.40 + 6.60

= 13.18 [μs]

When the task period is 500 μs, the variable access time is set to 19.08/500 ≈ 4%.

z

Processing in the Case That Actual Variable Access Time Became Longer

Than Set Value

If actual variable access time became longer than the set value, the following processing is per-

formed depending on the number of variable accesses in one task period.

Set a sufficiently long access time so that multiple variable accesses can be completed within a task

period.

Number of vari-

able accesses in

Processing

one task period

Multiple times

Variable accesses are executed for the number of times that can be completed within

the set variable access time. The rest of accesses that could not be done will be exe-

cuted in the next task period.

This means, the multiple variable accesses cannot be completed within the same task

period.

Once

Variable accesses continue even after the set variable access time is exceeded. This

means, the task execution time gets longer.

5-52

5 Designing Tasks

5-7

Errors Related to Tasks

This section describes the following errors.

• Task Period Exceeded

• Motion Control Period Exceeded

• Task Execution Timeout

• I/O Refreshing Timeout Error

Task Period Exceeded

A Task Period Exceeded error occurs if the task execution time exceeds the specified task period.

This is a minor fault level Controller error. Operation continues even when this error occurs.

It can occur for the primary periodic task and periodic tasks.

You can also disable the Task Period Exceeded errors with a setting. Use the Task Period Exceeded

Detection setting in the Task Settings of the Sysmac Studio. The default setting is to detect the error.

Task period

Task period

Task period

Task period

5

Primary

IO

UPG MC

IO

IO

UPG MC

periodic task

IO

UPG

MC

Task Period Exceeded

occurred.

Error name

Error level

Correction

Task Period Exceeded

Minor fault

Review the task settings and programs and download the project

again. Reset the error from the Sysmac Studio.

Even if the Task Period Exceeded Detection setting is disabled, information will be output to the follow-

ing system-defined variables if task processing is not completed within the period: Task Period

Exceeded Flag (_TaskName_Exceeded), Task Period Exceeded Count (_TaskName_ExceedCount),

Controller Error Status (_ErrSta), and the event log.

I/O is refreshed as follows according to what the I/O is for if task processing is not completed within the

task period.

I/O is for

I/O refresh operation if task processing is not completed within the task period

EtherCAT slave^*1

Outputs: The values from the previous period are output.

Inputs: Inputs are refreshed, but the input data is not updated in the executed user pro-

gram.

*1

This includes NX Units on EtherCAT Slave Terminals.

Precautions for Correct Use

If the Task Period Exceeded error occurs, shorten the programs to fit in the task period or

increase the setting of the task period.

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5 Designing Tasks

Motion Control Period Exceeded

A Motion Control Period Exceeded error occurs if the motion control processing (MC) is not completed

within the primary period (i.e., the motion control period) twice or more in a row. A partial fault level Con-

troller error will occur in the Motion Control Function Module. A Task Period Exceeded error will occur at

the same time.

Error name

Error level

Correction

Motion Control Period

Partial fault

Reduce the amount of processing in the programs or

Exceeded

increase the control period within the range that does not

adversely affect operation.

Task Execution Timeout

A Task Execution Timeout error occurs if task processing is not completed within the specified timeout

detection time.

This is a major fault level Controller error. Execution of the user program stops when the error occurs.

This error also occurs when normal task operation is not possible due to errors in program logic, such

as infinite loops.

Timeout Detection Time

Primary period

Primary period

Primary period

Primary period

Primary

IO

IO

periodic task

UPG

Infinite loop, etc.

Task Execution Timeout occurred.

Error name

Error level

Correction

Task Execution

Major fault

Review the task settings and download the user program again.

Timeout

The power supply must be cycled or the Controller reset.

I/O Refreshing Timeout Error

An I/O Refreshing Timeout Error occurs when I/O refreshing for the primary periodic task is not com-

pleted within the period twice or more in a row.

This is a major fault level Controller error. Execution of the user program stops when the error occurs.

Primary period

Primary period

Primary period

Primary period

Primary

M

M

IO

UPG

IO

UPG

periodic task

C

C

I/O Refreshing Timeout Error occurred twice or more.

Error name

Error level

Correction

I/O Refreshing

Major fault

Review the task settings and download the project again.

Timeout Error

The power supply must be cycled or the Controller reset.

5-54

5 Designing Tasks

5-8

Monitoring Task Execution Status and Task

Execution Times

You can use online operations from the Sysmac Studio to monitor the task execution status and task

execution times.

Monitoring Task Execution Status

You can monitor the execution status of the programs in all of the tasks (started/stopped) from the Sys-

mac Studio.

z Sysmac Studio Operation

Place the Sysmac Studio online with the Controller and select Configurations and Setup − Task

Settings. Click the Task Execution Status Monitor Button to display the following window.

5

5-55

5 Designing Tasks

Task Execution Time Monitor

You can monitor the execution time of each task from the Sysmac Studio.

z Values You Can Monitor from the Sysmac Studio

Connected to the Controller

5-56

5 Designing Tasks

Built-in EtherNet/IP Dialog Box for Simulator Connection

The parameters are listed in the following table.

Port that is used

Parameter

Description

Set values

Default

Built-in EtherNet/IP

Number of con-

This is the number of tag data

0 to 128

0

port on NY-series Con-

nections

link connections.

troller

Minimum RPI

This is the lowest packet inter-

1 ms to 10 s in

---

val (RPI) that is set for all of the

1-ms incre-

tag data link connections.

ments

You can monitor the following items.

Connected

5

Monitor item

Description

to the Con-

troller

Task execu-

Min.

The minimum value of the task execution time.

Displayed.

tion time*1

Average

The average value of the task execution time.

Max.

The maximum value of the task execution time.

Set period

The specified task period.^*2

Period exceeded

If the task execution time exceeds the task period (i.e., if the

Task Period Exceeded Flag system-defined variable is TRUE),

the amount by which the time was exceeded is displayed in the

bar. 2

Task execution count

Displays the number of executions of the task.

The value of the Task Execution Count system-defined variable is

displayed.

*1

This is the actual time required from the point that task execution was started until it was completed. This

interval includes both the time to execute other tasks and the time for system services that were executed

from when task execution was started until it was completed.

*2

This item is not displayed for event tasks.

Precautions for Correct Use

Always confirm operation while connected to the physical Controller to study the designs and

before starting actual system operation.

5-57

5 Designing Tasks

Meaning of the Task Execution Time and the Real Processing Time

of the Task

The Task Execution Time and Real Processing Time of Tasks that are displayed in the Monitor View for

the execution time of tasks are described in the following table.

Displayed time

Meaning

Task execution

This is the time from when the task period starts until task processing ends.

time

However, this includes the time when the periodic task is interrupted for execution of

tasks with higher execution priorities.

Execution

priority

Task period of primary periodic task

High

Primary

periodic task

a

Task period of periodic task

Periodic task

Interrupted.

Interrupted.

Interrupted.

Interrupted.

Low

b

a: Task execution time of primary periodic task

b: Task execution time of periodic task

5-58

5 Designing Tasks

5-9

Task Design Methods and I/O

Response Times

This section provides guidelines for designing tasks, information on estimating task execution times, an

example of task designing, and information on I/O response times.

The primary periodic task and periodic tasks of an NY-series Controller operate according to the speci-

fied task periods.

If the actual execution time exceeds the task period, an error occurs.

This section uses an example that consists of one primary periodic task to describe estimation and

appraisal methods.

Precautions for Correct Use

The task execution times in the physical Controller depends on the logic operations that are per-

formed in the user program, the presence of communications commands and data links, on

whether data tracing is performed, and on other factors.

Before starting actual operation, you must test performance under all foreseeable conditions on

the actual system and make sure that the task periods are not exceeded and that suitable com-

munications performance is achieved.

5

5-9-1

Checking the Task Execution Time

Always design your system so that the average and maximum task execution times that are estimated

with the methods that are described in this section sufficiently fit within the specified task periods.

z Desktop Calculations

First, refer to A-2 Calculating Guidelines for the Real Processing Times of Tasks for the NY-series

System to make a rough estimate of the average task execution time on paper.

You cannot estimate the maximum value on paper.

z Calculating Times on the Physical Controller

You can check the following values in the Task Execution Time Monitor when you are connected to

the physical Controller.

• The minimum, average, and maximum values of the task execution time

• Set period

• Task execution count

• Number of times the task period was exceeded (Task Period Exceeded Count)

The maximum values that are displayed on the Sysmac Studio are the results of operation on the

physical Controller.

As described previously, the maximum value of the task execution time varies depending on the

internal status of the physical Controller.

Additional Information

The average values of the task execution times that are displayed for task execution time moni-

toring are the averages for 10 task execution times.

5-59

5 Designing Tasks

5-9-3

System Input and Output Response Times

The times that are required for the system to produce an output after it receives an input are described

in this section.

The I/O response times depend on various conditions.

The input response times and output response times between external devices and the slaves and

Units must be added to the system I/O response times.

Sequence Control with Basic I/O Units

I/O refreshing between Basic I/O Units and external devices is performed in the task to which I/O

refreshing is assigned.

The I/O response times that include EtherCAT communications times are given below.

z Performing Control with the Programs in the Primary Periodic Task

The Controller makes a response in the following I/O response time.

Minimum I/O response time = Primary period

Example: Controlling Unit A and Unit B with the Primary Periodic Task

5

Unit A

Unit B

Primary period (t)

Primary

M

M

M

IO

UPG

IO

UPG

IO

UPG

periodic task

C

C

C

Task period 1 (e.g., t × 3)

Priority-16

UPG

periodic task

Note: The above diagram shows only one input and one output.

However, the I/O response time may be as follows depending on the timing of the input from the

Unit.

Maximum I/O response time = Primary period × 2

5-61

5 Designing Tasks

z Performing Control with the Programs in the Priority-16 Periodic Task

The Controller makes a response in the following I/O response time.

Minimum I/O response time = Priority-16 periodic task period

Example: Controlling Unit A and Unit B with the Priority-16 Periodic Task

Unit A

Unit B

IN

OUT

Primary period

Primary

IO

UPG MC

IO

UPG MC

IO

UPG MC

IO

UPG MC

periodic task

Task period

Priority-16

UPG

UPG

periodic task

Note: The above diagram shows only one input and one output.

However, the I/O response time may be as follows depending on the timing of the input from the

Unit.

Maximum I/O response time = Priority-16 periodic task period × 2

Sequence Control with EtherCAT Slaves

For EtherCAT slaves, EtherCAT communications with external devices is performed for I/O refreshing

in the primary periodic task.

The I/O response times that include EtherCAT communications times are given below.

z Performing Control with the Programs in the Primary Periodic Task

The Controller makes a response in the following I/O response time.

Minimum I/O response time = Primary period (= process data communications cycle)

Example: Controlling EtherCAT Input Slave A and EtherCAT Output Slave B with the Primary Peri-

odic Task

Slave A

Slave B

Process data

communications period =

Primary period (t)

Primary

M

M

M

IO

UPG

IO

UPG

IO

UPG

periodic task

C

C

C

Task period 1 (e.g., t × 3)

Priority-16

UPG

periodic task

Note: The above diagram shows only one input and one output.

However, the I/O response time may be as follows depending on the timing of the input from the

slave.

Maximum I/O response time = Primary period (= process data communications cycle) × 2

5-62

5 Designing Tasks

z Performing Control with the Programs in the Priority-16 Periodic Task

The Controller makes a response in the following I/O response time.

I/O response time = Priority-16 periodic task period

Example: Controlling EtherCAT Input Slave A and EtherCAT Output Slave B with the Priority-16

Periodic Task

Slave A

Slave B

IN

OUT

Process data

communications cycle

= Primary period (t)

Primary

IO

UPG MC

IO

UPG MC

IO

UPG MC

IO

UPG MC

periodic task

Task

period

Priority-16

UPG

UPG

periodic task

Note: The above diagram shows only one input and one output.

However, the I/O response time may be as follows depending on the timing of the input from the

slave.

Maximum I/O response time = Priority-16 periodic task period × 2

5

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