Profibus Dp Coupling; General Basics; Configuring; Configuring The Dp Master System On Fm 458-1 Dp - Siemens SIMATIC FM 458-1 DP User Manual

4.4

PROFIBUS DP coupling

4.4.1 General basics

Characteristics

4.4.2 Configuring

4.4.2.1

Configuring the DP master system on FM 458-1 DP

Application Module FM 458-1 DP - User Manual
A5E01078222-02 Edition 03.2009
FM 458-1 DP has the following characteristics on PROFIBUS DP:

Master
The FM 458-1 DP communications module can be operated on
PROFIBUS both alone (stand alone) and with other masters in multi-
master operation.

Shared input
Each slave connected to PROFIBUS DP is assigned just one master
(the parameterizing master) and at first can only communicate with
this master. Additional masters can read the slave input data using
the "Shared input". FM 458-1 DP supports this functionality as master
and slave.

SYNC and FREEZE
The outputs/inputs of several slaves can be read/written in
synchronism using the SYNC and FREEZE utilities. FM 458-1 DP
supports these utilities as master.

Equidistance (isochronous mode)
Equidistance (isochronous mode) is a feature of the PROFIBUS DP
which guarantees bus cycles which are always precisely the same
length.

Clock-cycle synchronism
The FM 458-1 DP and its user program can be synchronized to the
PROFIBUS clock cycle.

Slave-to-slave communications
The configured slaves can "directly" exchange data with one another
without being configured in the FM 458-1 DP.

Data lengths
A maximum of 244 bytes can be transferred in each direction and for
each slave.

Consistency
Data within a telegram is always consistent.
The DP master of the FM 458-1 DP is configured the same as for the
SIMATIC with HWConfig and when configuring the network. In this case,
there are no differences than when configuring another DP master (e.g.
CPU 315-2DP).
Configuring
4-15