Siemens SIMATIC ET 200AL System Manual page 206

Note
Safe electrical separation
Maintain safe galvanic isolation for voltages higher than SELV/PELV.
Note
Selection of the IO-Link master
If the safety-related shutdown is performed via the IO-Link master, ensure that the master
has the appropriate safety characteristics.
Note
IO-Link cable
Use a 3-wire cable for the connection of an IO-Link master with Port Class B and an IO-Link
device with Port Class A.
Limits of the higher-level safety circuit
The ET 200AL IO-Link modules do not perform any safety functions. Safety functions are
performed by the safety relay to bring the system into a safe state.
Adjust the operation inspection interval of the safety relay with relay output according to the
safety class.
Take the following measures if energy that is not provided by the higher-level safety circuit is
used to control the safety function.
Cover critical errors in the safety function that are not detected by the higher-level safety
circuit (e.g. 3SK1) with suitable safety measures. The "diagnostics" must be performed
indirectly via the controlled process.
Specifications for safety-relevant process data:
• Functionally safe
• Read via fail-safe inputs (e.g. F-DI)
• Fail-safe processing unit (e.g. F-CPU) for issuing commands
• Output through fail-safe outputs (e.g. F-DQ) to control the safety function
Requirements on the power supply
Operation requires a SELV/PELV power supply to limit overvoltages to L+ and M (24 V). This
measure prevents possible errors from the power supply side at the same time.
Select the power supply according to the requirements of the respective operating
instructions for the shutdown device and for the ET 200AL system.
You can find more information on safe SELV/PELV in the data sheets of the power supplies
used.
IO-Link I/O modules
System Manual, 08/2021, A5E48755395-AB
Safety-related shutdown of ET 200AL IO-Link modules
63