Allen-Bradley 1756-L61S ControlLogix 5561S, Справочное руководство

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18 Rockwell Automation Publication 1756-RM093J-EN-P - April 2018
Chapter 1 Safety Integrity Level (SIL) Concept
Figure 3 - Reliability Burden
System Reaction Time The system reaction time is the amount of time from a safety-related event as an
input to the system until the system sets corresponding outputs to their safe state.
Faults within the system can also have an effect upon the reaction time of the
system. The system reaction time is the sum of the following reaction times.
Each of the times listed above is variably dependent on factors such as the type of
I/O module and instructions used in the program.
Safety Task Reaction Time
The safety task reaction time is the worst-case delay from any input change
presented to the controller until the processed output is set by the output
producer. It is less than or equal to the sum of the safety task period and the safety
task watchdog.
Actuator
Controller
Output
Module
+V
Sensor
Sensor
40% of the
PFD
10% of the PFD
50% of the PFD
Input
Module
Actuator
+ + + +
Sensor
Reaction
Time
Input
Reaction
Time
Safety Task
Reaction
Time
Output
Reaction
Time
Actuator
Reaction
Time