Control And Monitoring Of The Actuator - Siemens SIMATIC ET200SP Function Manual

For this reason, a 1BA4 version of the 3SF1 position switch is used in the application example
described here.
See the figure below:
• 1st normally closed contact of actuator (state: door closed): 11 / 12
• 2nd normally closed contact of actuator (state: door closed): 21 / 22
• Normally closed contact / signaling contact of the solenoid (state: tumbler active): 41 / 42
• Control of the solenoid (state: door release inactive): E1 / E2
Figure 4-3
4.2.4

Control and monitoring of the actuator

In order to achieve PL e according to ISO 13849-1 or SIL 3 according to IEC 62061, the
shutdown of the machine is designed redundantly. Here, two SIRIUS 3RT2 contactors are
used and their correct functioning is monitored by the failsafe controller (feedback circuit
monitoring) through their auxiliary contacts (mirror contacts). The mirror contacts can be
read by a standard input module.
If one of the two contactors welds, the second contactor can continue to ensure a safe
shutdown. The welding of a contact is detected by the feedback circuit monitoring at the
next signal change, and a new switch on is prevented until the fault is rectified.
Safety engineering with AS‑Interface in the SIMATIC ET 200SP, including typical circuit diagram
Function Manual, 08/2020, A5E44991382002A/RS-AB/002
3SF1324-1SD21-1BA4 internal circuit diagram
Circuit diagram example
4.2 Operating principle
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