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Reaction Times Section 3-2
3-2 Reaction Times
This section describes how to calculate reaction times (safety response per-
formance) for the G9SP-series Controller.
3-2-1 Reaction Time Concepts
Reaction Time
The reaction time is the time required to stop machine operation in a worst-
case scenario considering the occurrence of faults and failures in the safety
chain. The safety chain is the logical connections that are required to achieve
a safety function, including the Safety Input device, G9SP-series Controller,
and Safety Output device. The reaction time is used to calculate the safety
distance.
3-2-2 Local Input and Local Output Reaction Times
This section describes the local Safety I/O reaction time for the G9SP-series
Controller. When calculating the reaction time of the overall safety chain, cal-
culate separately the reaction times of safety sensor and switches, such as
light curtains, and actuators, such as safety relays.
Elements for Calculating the Reaction Time
The reaction time for local Safety I/O on the G9SP-series Controller depends
on the following conditions. Check the conditions and values before calculat-
ing the reaction time.
■ Cycle Time
The cycle time depends on the size and contents of the program.
■ Input OFF Delay Time
If an OFF delay is set for an input, e.g., to prevent chattering, the OFF delay
time must be added to the reaction time.
Precautions for Correct Use
• If the cycle time changes as the result of changes to the program, calculate
the reaction time again.
• If an Off-Delay Timer function block is used in the program or if loop-back
connections are used, they must also be added to the reaction time.
Checking the Safety Input Devices, Cycle Time, and Input OFF Delay Times
The cycle time and input OFF delay times can be checked on the configura-
tion report that is output from the G9SP Configurator.
G9SP-series
Safety Controller
Safety Sensor/
Switch
Actuator
Sensor/Switch
reaction time
Actuator
reaction time
Local input or
output reaction
time
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