Performance Features; Profibus - Siemens SIMATIC FM 458-1 DP User Manual

Product description
2.3.2

Performance features

2.3.3

PROFIBUS

WARNING
!
2-34
 Master- or slave interface for PROFIBUS-DP
incl. the functions "Shared Input", SYNC, FREEZE
 Data transfer rates from 9.6 kbit/s to 12 Mbit/s
 Max. 127 slaves can be connected (dependent on the configuration)
 Telegram length of max. 244 bytes per slave
 RS 485 interface for PROFIBUS-DP, floating
 RS 232 interface to parameterize the bus node
 Two displays (LED) to indicate the operating status of the
communications interface and the bus activity
 DP master with COM PROFIBUS
 LE bus
The LE bus ensures fast data transfer between the FM 458-1 DP
application module and its expansion modules.
P bus
The peripheral bus (P bus) is the parallel SIMATIC backplane bus,
which only provides the power supply for the EXM 448.
The EXM 448 manifests the following behavior at the PROFIBUS DP
interface which is not in conformance with the SIMATIC system:
 If the FM 458-1 DP or the SIMATIC CPU goes to STOP within the
first minute after starting, then the EXM 448 sends, for up to one
minute, the last actual data to the slaves along PROFIBUS.
Application Module FM 458-1 DP - User Manual
A5E01078222-02 Edition 03.2009