Siemens SIMATIC NET S7-300 Operating Instructions

Autonegotiation
Autonegotiation means the automatic detection of the functionality of the port at the opposite
end. Using autonegotiation, network components or end devices can detect the functionality
available at the port of a partner device allowing automatic con󹪝guration of di󹪜erent types of
device. With autonegotiation, two components connected to a link segment can exchange
parameters and set themselves to match the supported communication functionality.
Note
Devices not supporting autonegotiation must be set to 100 Mbps/ half duplex or 10 Mbps half
duplex.
Note
The CSM 377 is a plug-and-play device that does not require settings to be made for
commissioning.
Auto polarity exchange
If the pair of receiving cables are incorrectly connected (RD+ and RD- swapped over), the polarity
is adapted automatically.
MDI /MDIX autocrossover function
The advantage of the MDI /MDIX autocrossover function is that straight-through cables can be
used throughout and crossover Ethernet cables are unnecessary. This prevents malfunctions
resulting from mismatching send and receive wires. This makes installation much easier for the
user.
Note
Please note that the direct connection of two ports on the switch or accidental connection over
several switches causes an illegal loop. Such a loop can lead to network overload and network
failures.
Product properties
3.4 TP ports
Compact Switch Module CSM 377
Operating Instructions, 06/2022, A2B00073499-02 15

Siemens SIMATIC NET S7-300 Specifications

General

Product Type Designation	SIMATIC NET S7-300
Mounting	DIN rail mounting
Protection Class	IP20
CPU Models	Various models available (e.g., CPU 312, CPU 314)
Communication Interfaces	MPI, PROFIBUS DP
Power Supply	24 V DC power supply required. Different power supply modules available.
I/O Modules	Digital input modules, digital output modules, analog input modules, analog output modules
Programming	STEP 7 software
Supply Voltage	24V DC or 120/230V AC (depending on model)
Digital Inputs	Available via digital input modules
Digital Outputs	Available via digital output modules
Analog Inputs	Available via analog input modules
Analog Outputs	Available via analog output modules
Communication Functions	MPI, PROFIBUS DP, Ethernet (depending on model)
Protocols	MPI, PROFIBUS DP, TCP/IP (depending on model)
Operating Temperature	0°C to 60°C
Storage Temperature	70 °C
Memory	Depends on CPU model (e.g., 32 KB to 1.5 MB)