Siemens SIMATIC S7-1500 System Manual page 67

5.2 Additional rules and regulations for operation of the S7-1500/ET 200MP with fail-safe modules
To achieve Cat.4, sensors must be connected via two channels.
In the case of fail-safe input modules, a "0" value 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 respective actuator when it is in the "0" state (EMERGENCY-STOP button
pressed).
Duration requirements for sensor signals
Observe the following requirements for sensor signals:
• In order to ensure the correct detection of the sensor signals via fail-safe modules with
• In order for pulses to be detected with certainty, the time between two signal changes
S af e detection of inputs through F-modules
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 duration of 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 section "Response times" of the
respective F-module.
The maximum permitted switching frequency of the sensor signals results from the minimum
duration.
Additional requirements for actuators
The fail-safe output modules test the outputs at regular intervals. The F-module briefly
switches off the activated outputs and, if necessary, switches on the deactivated outputs.
You can assign the maximum duration of the test pulses (dark and light period) with
parameters.
Automation system
System Manual, 09/2016, A5E03461182-AD
WA RNING
WA RNING
inputs, you need to make sure that the sensor signals are output for a minimum
duration.
(pulse duration) must be greater than the PROFIsafe monitoring time.
Wiring
67