Integration In The Automation Landscape; What Is A Distributed I/O System - Siemens Simatic 6ES7 157-0AD81-0 A0 Series Manual

Product Overview
Y link
The Y link consists of two IM 157 interface modules and a Y coupler that are
interconnected via bus modules.
The Y link provides a gateway from the redundant DP master system of an
S7-400H to a non-redundant DP master system. This permits devices with only
one PROFIBUS-DP interface to be connected to an S7-400H as a switched I/O
system.
1.2

Integration in the automation landscape

1.2.1

What is a distributed I/O system?

Distributed I/O devices – area of application
When a system is set up, the inputs and outputs to and from the process are often
located centrally in the automation system.
If the inputs and outputs are located at a considerable distance from the
automation system, this may lead to long and complex cable runs and
electromagnetic interference may impair system reliability.
A distributed I/O is the ideal solution for such systems:
S The PROFIBUS-DP master is located centrally.
S The I/O devices (inputs and outputs) operate locally on a distributed basis.
S The high-performance PROFIBUS-DP bus system with its high transmission
rates ensures that the controller CPU and I/O devices communicate smoothly.
What is PROFIBUS-DP?
PROFIBUS-DP is an open bus system according to IEC 61784-1:2002 Ed1 CP 3/1
with the "DP" transmission protocol (DP being the German abbreviation for
distributed I/O).
Physically, PROFIBUS-DP is either an electrical network based on a shielded
two-wire line or an optical network based on a fiber optic cable.
The "DP" transmission protocol allows very rapid, cyclic exchange of data between
the controller CPU and the distributed I/O devices.
1-2
DP/PA Link and Y Link Bus Couplings
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