Siemens SIMATIC ET 200AL System Manual page 1162

Behavior during operation
After commissioning, you may exchange or jumper IO devices as long as the IO devices do
not have a PROFINET device name that is used for a different IO device in the project.
Otherwise, incorrect assignment of PROFINET device names in the neighborhood or further
vicinity of the IO device can occur.
Wrong PROFINET device name
When the "Permit overwriting of PROFINET device names of all assigned IO devices"
option is enabled, incorrectly connected devices can be assigned an incorrect PROFINET
device name from the configuration.
Depending on the connected I/O, there is risk of death, severe injuries or damage caused
by malfunctions.
To rule out any danger, check whether the suitable replacement device has been
connected in case of a device replacement and whether the port interconnection matches
the configured preset topology.
Typical source of danger
When replacing an IO device ("standard case"), it is almost guaranteed that the replaced
device will be connected according to the configured port interconnection.
The figure below shows a scenario whereby the connections of two identical PROFINET
cables are swapped at two switch ports. Because the IO controller assigns the device names
according to the preset topology, the incorrect connection of the devices has serious effects
on the naming.
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH
WARNING
5.8 Device replacement without exchangeable medium
Functions
215