Fundamentals - Siemens S7-400 Installation Manual

5.2

Fundamentals

Station = Node
Declaration: All the stations you connect in a network are referred to as nodes in
the following.
Segment
A segment is a bus cable between two terminating resistors. A segment can
contain up to 32 nodes. Furthermore, a segment is limited by the permissible cable
length according to the transmission rate.
Baud Rate
The baud rate (transmission rate) is the speed at which data is transmitted,
expressed in terms of bits per second.
• Baud rates of 19.2 kbps to 12 Mbps are possible for interfaces of the type
MPI/DP.
• Transmission rates of 9.6 kbps to 12 Mbps are possible for interfaces of the
type PROFIBUS-DP.
Note
If you change the parameter assignment of the MPI/DP interface transmission rate,
the new transmission rate remains set even after memory reset, voltage failure or
removing/inserting the CPU.
Connectable Nodes
Programming devices (PGs)
Operator interfaces (SIMATIC-OP),
WinCC
S7-400/M7-400
S7-300/M7-300
* Not recommended in DP operation
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
MPI
Programming devices (PGs)
Operator panels (OPs)*
PROFIBUS-DP master
PROFIBUS-DP slaves
Networking
PROFIBUS DP
5-3