Siemens Simantic ET200SP System Manual page 79

5.2 Additional rules and regulations for the operation of the ET 200SP with fail-safe modules
Additional sensor requirements
General rule: To achieve SIL3/Cat. 3/PLe, a single-channel sensor is adequate. However, to
achieve SIL3/Cat. 3/PLe with a single-channel sensor, the sensor itself must be
SIL3/Cat. 3/PLe-capable; otherwise the sensor must be connected by two channels to
achieve this safety level.
To achieve SIL3/Cat. 4/PLe, sensors must be connected by two channels.
In the case of fail-safe input modules, the value "0" is output to the F-CPU after detection of
faults. You therefore need to make sure that the sensors are implemented in such a way as
to ensure the reliable reaction of the safety program when the sensor is in the "0" state.
Example: In its safety program, an EMERGENCY-STOP sensor must achieve the
shutdown of the relevant actuator when it is in the "0" state (EMERGENCY-STOP button
pressed).
Additional requirements for sensors for fail-safe motor starters
Only single-channel sensors that fulfill the required safety category themselves may be
connected to the fail-safe motor starter's F-DI. Fail-safe laying must be observed in
accordance with the required safety category.
Duration requirements for sensor signals
Observe the following requirements for sensor signals:
• To ensure the correct detection of the sensor signals via fail-safe modules with inputs,
• For pulses to be detected with certainty, the time between two signal changes (pulse
Reliable detection by F-modules with inputs
The minimum duration of sensor signals for F-modules with inputs depends on the
configured input delay, the parameters of the short circuit test of the sensor supplies, and the
configured discrepancy behavior for 1oo2 evaluation. The signal must be greater than the
maximum response time of the configured application. Information on calculating the
maximum response time can be found in the section "Response times" of the relevant F-
module.
The maximum permitted switching frequency of the sensor signals results from the minimum
duration.
Distributed I/O system
System Manual, 12/2016, A5E03576849-AG
WARNING
WARNING
you need to make sure that the sensor signals are output for a minimum duration.
duration) must be greater than the PROFIsafe monitoring time.
Wiring
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