
Safety engineering
Response times
68
EDS94AYAF EN 1.0
1.8
Response times
In order to detect the response time to a safety function the entire system must be
considered. The following is relevant:
ƒ
Response time of the connected sensors.
ƒ
Input delay of the safety inputs.
ƒ
Internal processing time.
ƒ
When a safety bus is used:
– Monitoring time for cyclic services.
– Monitoring time in the safety PLC.
– Processing time in the safety PLC.
ƒ
Delay times due to further components.
μ
C
μ
C
S
SF
t = 0
t
1
t
2
0
1
t
ps
t
4
2
3
t
3
t
5
t
i
lcu12x_352
Fig. 1−13
Response times to the request of a safety function
Standard device
Safety module
Safety PLC
Safety bus
m
C Microcontroller
S
Safety sensor technology
SF
Activated safety function