AWT210 PROFIBUS PA 2-WIRE TRANSMITTER | COM/AWT210/PROFIBUS-EN REV. A
7
6 Installation
All devices are connected in a bus structure ('line') as shown in
Figure 1.
The number of transmitters or devices that can be connected
to a bus is primarily dependent on the power consumption of
the transmitters or devices, the type of cable, the number of
spurs, the total cable length of the bus and intrinsic safety
requirements.
Each end of a segment must be terminated by an active bus
terminating resistor. Both bus terminators must always be
powered to ensure fault-free operation, therefore it is strongly
recommended that they are connected to a back-up power
supply.
The PROFIBUS PA furnishes transmitter power and can be
configured as a point-to-point, tree, Daisy Chain, or Trunk/
Spurs network. Modulating the base quiescent current
generates the communication signals. The quiescent current
value is used as a reference to establish the number of devices
that can be installed on a single bus line.
Data is transmitted over the bus using digital, bit synchronous
Manchester II coding at a baud rate of 31.25 kbit/sec.
Figure 1 Typical PROFIBUS network
Engineer
Control
Profibus-DP
Profibus-PA
DP/PA link
AWT210
2-wire transmitter
Operate
Operational
level
Master
level
Slave
level
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