Siemens RWF55.5 User Manual page 75

Wiring and bus
termination
Basic functions
Building Technologies Division
Infrastructure & Cities Sector
DGND
RxD/TxD-N
RxD/TxD-P
VP
Connector
Figure 39: Wiring and bus termination
Profibus DP is designed for fast data exchange at field level. In this case, the central
control devices (such as the PLC/PC) communicate with distributed field devices (such
as I/Os, screen recorders, and controllers) via a fast serial connection. Data exchange
with these distributed devices is usually cyclical.
The communication functions required for this are defined by basic Profibus DP
functions in accordance with IEC 61158 and IEC 61784.
The central control device (master) reads input messages from the slaves cyclically and
writes output messages to the slaves cyclically. The bus cycle time must be shorter
than the program cycle time of the central PLC. As well as cyclical user data transfer,
Profibus DP is able to carry out high-performance diagnostics and commissioning
functions.
Technology transfer

RS-485 twisted 2-wire line

Baud rate of 9.6 kbit/s upto 12 Mbit/s
Bus access

Master and slave devices, maximum 126 nodes on a bus (with repeater)
Communication

Point-to-point (user data traffic)

Cyclical master-slave user data traffic
Operation states

Operate Cyclical transfer of input and output data

Clear Inputs are read; outputs remain in a safe state

Stop Only master-master data transfer is possible
Synchronization

Sync-Mode Not supported by the RWF55

Freeze-Mode Not supported by the RWF55
Functionality

Cyclical user data transfer between DP master and DP slave(s)

Dynamic activation or deactivation of individual DP slaves

Checking of DP slave configuration

Address assignment for DP slaves via the bus

Configuration of DP master via the bus

Maximum 246 bytes of input/output data possible per DP slave
User Manual RWF55...
12 Profibus-DP interface
390 Ohm
220 Ohm
7867z22e/0712
390 Ohm
Protective
earth PE
Wiring
VP (pin 6)
RxD/TxD-P (pin 3)
RxD/TxD-N (pin 8)
DGND (pin 5)
Bus termination
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CC1U7867en
05.11.2013