Topology; Maximum System Extension; Single-Master Systems; Multi-Master Systems - turck IO-LINK MASTER User Manual

System overview

Single-Master systems

With mono-master systems merely a single master on the bus is active during bus operation.
The PLC is the central control component. The slaves are coupled decentrally to the PLC via
the transmission medium. With this type of system configuration the shortest bus cycle times
are achieved.

Multi-Master systems

In multi-master operation there are several masters on the bus. These form independent sub-
systems, consisting of one DPM1 each and the associated slaves, or additional configuration
and diagnostic devices. The slave input and output data can be read by all DP masters.
Writing of outputs is reserved to a single DP master (the assigned DPM1 during configuration).
Multi-Master systems achieve an average bus cycle time. In time-critical applications you
should monitor the bus cycle time via a connected diagnostic tool.

Topology

PROFIBUS-DP communicates via a shielded 2-wire cable according to the RS485 standard.
The network topology accords to a line structure with active bus terminators on both ends.

Maximum system extension

PROFIBUS-DP is suited for connection of a large number of I/O points. Up to 126 addressable
bus nodes enable connection of thousands of analogue and digital I/O points within a
network.
PROFIBUS-DP allows a maximum of 32 nodes per segment; please note that masters and
repeaters always count as nodes. One segment is defined as the bus section between two
repeaters. If no repeaters are used, the entire network corresponds to one segment.
Segments must comply with the specified maximum length and the specified transmission
rates. Up to nine repeaters, type "REP-DP0002" may be connected within a network. The
maximum length of a bus line within a segment and the number of repeaters are listed in the
following table.
Table 1: Communication rate
Maximum
System expan-
9.6 kbps
sion
PROFIBUS-DP
19,2 kbps
93,75 kbps
187,5 kbps
500 kbps
1.5 Mbps
12 Mbps
D301171 - IO-Link master 1108
Length of bus line Max. no. of
1200 m
1200 m
1200 m
1000 m
400 m
200 m
100 m
Attention
The maximum number of 32 bus nodes may not be exceeded without a repeater.
Max. no. of nodes
repeaters
2 126
2 126
2 126
2 126
4 126
6 126
9 126
1
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