Siemens SIMATIC ET 200AL System Manual page 310

Product overview
2.3 Functions
Device replacement without programming device
IO devices with this function can easily be replaced. You do not have to assign the device
name with the PG.
The replaced IO device is assigned the device name by the IO controller and not by the
programming device. The IO controller uses the configured topology and the neighboring
relationships determined by the IO devices for this purpose. To do this, all devices involved
must support the LLDP protocol (Link Layer Discovery Protocol). The configured target
topology must match the actual topology.
IO devices which were already used in another configuration must be reset to factory settings
before being reused.
Media redundancy
Function for safeguarding communication and plant availability. Redundant transmission
lines (ring topology) ensure that another communication path is made available in the event
of a transmission section failure.
Shared device
A shared device is an IO device that provides its data to up to four IO controllers.
The "Shared device" function allows the modules or submodules of an IO device to be divided
up among different IO controllers. Thus allowing flexible automation concepts. You have, for
example, the possibility of combining I/O modules lying near other into an IO device.
When operating as a shared device, there might be temporary delays in the update of the IO
data when establishing or terminating additional communications relationships to an IO
controller.
You can find additional information in the STEP 7 online help and the manual and in the
function manual PROFINET with STEP 7 V14
(http://support.automation.siemens.com/WW/view/en/49948856).
Cabling with fixed connection setting
If you configure a fixed connection setting for the port in STEP 7, you also have to disable
"Autonegotiation/Autocrossover". By disabling "Autonegotiation/Autocrossover" you speed up
establishment of the communication path.
14
IM 157-1 PN (6ES7157-1AB00-0AB0)
Equipment Manual, 05/2021, A5E32347036-AE