Omron NX-SID800 User Manual

4 - 5
4 Calculating Safety Reaction Times
NX-series Safety Control Unit User’s Manual (Z930)
4-2 Safety Task
4
4-2-1 Safety Task
4-2 Safety Task
This section describes the safety task of the Safety CPU Unit.
The safety task period of the Safety CPU Unit affects the safety reaction times.
The safety task is used to assign an execution condition to a series of processes, such as for data
exchange with Safety I/O Units and safety program execution.
The Safety CPU Unit executes one safety task.
The safety task is executed on a fixed period.
More than one program
*1
can be assigned to the safety task. The programs that are assigned are exe-
cuted in the order that they are assigned. Execution of all of the programs assigned to the task is called
program execution.
Data exchange between the Safety CPU Unit and Safety I/O Units is called communications receive
processing and communications send processing.
The following operation is performed for the safety task.
Input data processing for I/O refreshing, user program execution, and output data processing for I/O
refreshing are performed repetitively, i.e., each safety task period.
The safety task period is the time interval for execution of the safety task. The upper limit of the safety
task period setting is 100 ms. A building error will occur for any safety program that requires a safety
task period that is longer than 100 ms. If that occurs, change the safety program.
4-2-1 Safety Task
*1. There is no limit to the number of programs.
Type of task
Number
of tasks
Task execu-
tion priority
Execution condition Main processing contents
Safety task 1 None The safety task is executed once
every safety task period during oper-
ation in RUN or DEBUG mode.
Communications receive
processing, program execu-
tion, and communications
send processing
4-2-2 Operation of Safety Task
Safety task period (fixed)
Program
execution
Safety task period (fixed)
Communications
receive
processing
Communications
receive
processing
Communications
receive
processing
Communications
send processing
Program
execution
Communications
send processing

Omron NX-SID800 Specifications

General

Brand	Omron
Model	NX-SID800
Category	Controller
Language	English