Siemens SIMOTION D410 DP - Connection Rules in the PROFIBUS Subnet

Unplugging the bus connector
You can remove the bus connector with a looped-through PROFIBUS cable from the
PROFIBUS DP interface at any time, without interrupting data traffic on the bus.
NOTICE
Data communication disturbed because bus terminator missing
A bus segment must be terminated at both ends with a terminating resistor. This is not the
case
if the last bus connector node is de-energized, for example. Because the bus connector
takes its voltage from the station, this terminating resistor is ineffective.
Make sure that the stations at which the terminating resistor is connected are always
energized.
6.9.6 Connection rules in the PROFIBUS subnet
Introduction
There are a number of rules for configuring and installing cables for PROFIBUS networks to
ensure
seamless communication over PROFIBUS. These rules apply to both configuring and
cabling as well as address assignment for the different network nodes.
Connection rules
● Before you interconnect individual nodes in a subnet, you must assign a unique PROFIBUS
address to each node.
● Narrow down the number of nodes by limiting the PROFIBUS addresses to the highest
address in the network.
Tip: Mark the address on the housing of all nodes in a subnet. Then you can always see
which address is assigned to which node in your system.
● Connect all nodes in a subnet "in a series". No spur lines may be routed to the
PROFIBUS DP.
In addition, connect the programming devices and SIMATIC HMI devices to the subnet in
a series for commissioning or maintenance work.
● If you are running more than 32 nodes in one subnet, you must couple the bus segments
via RS 485 repeaters (see also the description of the RS 485 repeater in the reference
Manual,
SIMATIC Automation Systems S7-300, Module Data ).
In a PROFIBUS subnet, all bus segments combined must have at least one DP master and
one DP slave.
● Use RS 485 repeaters to connect ungrounded bus segments and grounded bus segments.
● The maximum number of nodes per bus segment decreases with each RS 485 repeater.
This means that when a bus segment contains an RS 485 repeater, the bus segment can
contain no more than 31 additional nodes. However, the number of RS 485 repeaters does
not affect the maximum number of nodes on the bus.
Connecting
6.9 Connecting the PROFIBUS DP interface (410 DP only)
SIMOTION D410
Manual, 04/2014 81