REXROTH IndraDrive Fc FCS01, Руководство по эксплуатации

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Rexroth IndraDrive FCS01.1 Control Communication - Field Busses and Protocols
15-3
DOK-INDRV*--FCS01*****-IB01_EN-P
For the PROFIBUS DP, the following transmission services are defined:
Transmission
service Description
SDR Send and request data with acknowledge .
In a message cycle, the master transmits output data to a
slave and receives back the input data in the same cycle.
SDN Send data with no acknowledge
allows for transmission of broadcast telegrams
(unacknowledged telegrams).
Fig. 15-2: Transmission services
Profibus Master
PROFIBUS Master are field devices which take the initiative for data
exchange with field services acting as slaves. A master has the sole
access rights to the slaves on a bus (in case of several masters, the
respective master must have access right).
All data a PROFIBUS Master needs for exchanging data with the slaves
(e.g. I/O area) must be generated before system start and loaded into the
master (
→
GSD file).
The master primarily has the following tasks:
•
data exchange with the projected slaves
•
coordination of bus access
•
anticipation of error handling
•
making slave data available to the user.
The PROFIBUS DP Master is avaible as
•
module within a PLC
•
CPU module with integrated PLC
•
standard PC modules
•
stand-alone-boards
Profibus Bus Description
Bus structure
Elements Description / data
Bus elements Topology serial bus system
Nodes max. 126 nodes in the exchange of user data
Segments max. 32 nodes per segment
Repeater Required for 33 nodes or more to connect
segments.Recommendation: Do not connect more than 3
repeaters in series.
Interface Via serial interface RS 485
Bus terminator At both ends with 120
Ω Ω Ω Ω
resistors
between RS485 + and RS485 -
Abb. 15-3: Bus structure