Omron sysmac NX Series User Manual page 543

10-2 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.
10-2-1
Safety Task
The safety task is used to assign an execution condition to a series of processes, such as for data
exchange with the Safety I/O Units and the CIP Safety target device, as well as for safety program
execution.
The Safety CPU Unit executes one safety task.
The safety task is executed on a fixed period.
More than one program
cuted in the order that they are assigned. Execution of all of the programs assigned to the task is
called "program execution".
*1. There is no limit to the number of programs.
Data exchange between the Safety CPU Unit and, the Safety I/O Units and the CIP Safety target de-
vice is called "communications receive processing" and "communications send processing".
Type of Number
task of tasks
Safety 1
task
10-2-2
Operation of Safety Task
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.
Safety task period (fixed)
Communications
Program
receive
execution
processing
The safety task period is the time interval at which the safety task is executed. 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.
10-2-3
Minimum Safety Task Period
The minimum safety task period is automatically calculated by the Sysmac Studio and displayed in the
Minimum safety task period in the Task Settings.
NX-series Safety Control Unit/Communication Control Unit User's Manual (Z395)
*1
can be assigned to a safety task. The programs that are assigned are exe-
Task exe-
cution pri- Execution conditions
ority
None The safety task is executed once
every safety task period during op-
eration in RUN or DEBUG mode.
Communications Communications
send receive
processing processing
10 Calculating Safety Reaction Times
Communications receive proc-
essing, program execution, and
communications send processing
Safety task period (fixed)
Communications
Program
send
execution
processing
Main processing contents
Communications
receive
processing
10-5
10