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Profibus DP
The Profibus DP is a linear bus with a centralized access procedure
of the Master/Slave type. Only Master stations, also known as active
stations, have access rights to the bus. The Slave or passive stations
can only respond to prompts.
The physical connection is a single shielded twisted
pair, but fiber optic interfaces are available to create tree, star,
or ring structures. Compared to the ISO model, only layers 1, 2 are
implemented, since access from the user interface is made directly
to the link layer via simple mapping of variables.
INTERBUS
The INTERBUS bus is a serial link type fieldbus for sensors and actuators
which conforms to the requirements of an industrial environment. The
topology of the INTERBUS bus is designed as a ring system with master/slave
central access procedure. It is subdivided into three parts:
- The remote bus (bus devices use RS 485 point-to-point
connection).
- The installation remote bus (remote bus tap link
via a bus terminal module). Its technology is particularly suitable
for IP 65 dust and damp proof systems.
- The local bus with TTL technology
is particularly suitable for buses within a control cabinet.
Each
bus subscriber comprises a transmitter and a receiver. The INTERBUS
system is like a data ring and has the structure of a shift register
distributed on the bus. With its registers, each module constitutes
a component of this shift register ring. The INTERBUS master circulates
the data in series on this ring.
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