Siemens Simatic S7-1500 / ET 200MP - Page 154

Wiring
7.2 Additional rules and regulations for operation of the S7-1500/ET 200MP with fail-safe modules
Automation system
System Manual, 01/2023, A5E03461182-AK
153
Duration requirements for sensor signals
WARNING
Observe the following requirements for sensor signals:
• In order to ensure the correct detection of the sensor signals via fail-safe modules with
inputs, you need to make sure that the sensor signals are output for a minimum
duration.
• In order for pulses to be detected with certainty, the time between two signal changes
(pulse duration) must be greater than the PROFIsafe monitoring time.
Safe detection of inputs through F-modules
The minimum duration of sensor signals for fail-safe modules with inputs is dependent:
• On the parameters assigned for input delay
• On the parameters of the short-circuit test of sensor supplies.
• On the configured discrepancy behavior with 1oo2 (2v2) 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, briefly switches on the deactivated
outputs. You can assign the maximum duration of the test pulses (dark and light period) with
parameters.
High-speed actuators may briefly drop out or be activated during this test. If your process
does not tolerate this, set the pulse duration of the light or dark test correspondingly or use
actuators that have sufficient lag.
WARNING
If the actuators switch voltages greater than 24 V DC (e.g. 230 V AC), the outputs of a fail-
safe output module and the parts carrying a higher voltage must be electrically isolated
(acc. to standard IEC 60664-1).
This is generally the case with relays and contactors and you must pay particular attention
to this with semiconductor switching devices.
Technical specifications of sensors and actuators
Refer to the manuals of the fail-safe modules for technical specifications to assist you in
selecting sensors and actuators.