Siemens SIMATIC ET 200AL System Manual page 47

Connection of a digital output with a digital input
NOTICE
Pay attention to the potential group
When a digital output is connected to a digital input, pay attention to the potential groups.
Depending on the configuration, 1M and 2M may then be connected, resulting in
elimination of the electrical isolation between 1L+ and 2L+. The possible compensating
currents can destroy the digital module.
Note potential groups for safety-related shutdown
When a digital output is connected to a digital input, pay attention to the potential groups.
Depending on the configuration, 1M and 2M can then be connected, which leads to
elimination of the electrical isolation between 1L+ and 2L+.
The safety-related shutdown is not permitted if the electrical isolation is eliminated.
Cable protection
According to IEC 60364, cable protection is required, i.e. you must always secure the
incoming lines externally.
You must secure all incoming supply voltages with a UL/IEC approved 24 V DC/4 A fuse
(trigger characteristic type B or C).
Distributed I/O system
System Manual, 08/2021, A5E31861578-AJ
WARNING
5.4 Electrical configuration of the ET 200AL
Connecting
45