75/93
Building Technologies Division
User Manual RWF55...
CC1U7867en
Infrastructure & Cities Sector
12 Profibus-DP interface
05.11.2013
DGND
RxD/TxD-P
RxD/TxD-N
VP
VP (pin 6)
RxD/TxD-P (pin 3)
RxD/TxD-N (pin 8)
DGND (pin 5)
390 Ohm
220 Ohm
390 Ohm
Protective
earth PE
Connector Wiring Bus termination
7867z22e/0712
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
Wiring and bus
termination
Basic functions