Siemens SIMATIC NET SCALANCE XR-300 - Page 71

Pin assignment
The following table shows the pin assignment of the RJ45 connectors.
Pin number Assignments for ports up to RJ45 connector
Max. 100Mbps Max. 1000Mbps Max. 10000Mbps
Pin 1 RD+ D1+ D1+

Pin 2 RD- D1- D1-
Pin 3 TD+ D2+ D2+
Pin 4 n. c. (Not connec‐
ted)
D3+ D3+
Pin 5 n. c. (Not connec‐
ted)
D3- D3-
Pin 6 TD- D2- D2-
Pin 7 n. c. (Not connec‐
ted)
D4+ D4+
Pin 8 n. c. (Not connec‐
ted)
D4- D4-
MDI / MDI-X autocrossover
With the MPI/MDI-X autocrossover function, the send and receive contacts of an Ethernet port
are assigned automatically. The assignment depends on the cable with which the
communications partner is connected. This means that it does not matter whether the port is
connected using a patch cable or crossover cable. This prevents malfunctions resulting from
mismatching send and receive wires. This makes installation much easier for the user.
Note
Formation of loops
Please note that the direct connection of two ports on the IE switch or accidental connection
over several IE switches causes an illegal loop. Such a loop can lead to network overload and
network failures.
Autonegotiation
Autonegotiation means the automatic detection/negotiation of the transmission rate and the
operating mode of ports at the opposite end. This makes it possible to con󹪝gure di󹪜erent devices
automatically.
Connecting up
6.6Industrial Ethernet
SCALANCE XR-300
Operating Instructions, 03/2023, C79000-G8976-C586-02 71