Product overview
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1.1
Distributed I/O stations
Distributed I/O stations - Area of application
When a system is set up, it is common for the inputs to and outputs from the process to be
incorporated centrally in the automation system.
If the inputs/outputs are located at greater distances from the automation system, the wiring
can become very extensive and complex, and electromagnetic interferences can impair
reliability.
In such systems, it is often advisable to use distributed I/O stations:
● The controller CPU is located centrally.
● the I/O devices are distributed on site
● The powerful PROFIBUS DP with its high data transmission rates ensures smooth
communication between the controller CPU and the I/O devices.
● Less installation effort since less cables are required.
PROFIBUS DP
PROFIBUS DP is an open bus system based on
IEC 61784-1:2002 Ed1 CP 3/1 with the "DP"
transmission protocol (DP stands for distributed peripheral I/O).
Physically, PROFIBUS DP is either an electrical network based on a shielded two-wire cable
or an optical network based on a fiber-optic cable.
The "DP" protocol allows fast, cyclic data exchange between the control CPU and the
distributed I/O devices.
PROFIBUS RS 485-IS
In contrast to PROFIBUS DP, PROFIBUS DP RS 485-IS is intrinsically safe (protection type
- intrinsically safe i). The RS 485 IS coupler ensures intrinsic safety and acts as a safety barrier.
You can find addtional information on PROFIBUS RS 485-IS in the "PROFIBUS RS485‑IS
User and Installation Guideline (
DP master and DP slaves
The link between the control CPU and the distributed I/O devices is the DP master. The DP
master exchanges data with the distributed I/O devices via PROFIBUS DP and monitors the
PROFIBUS DP.
The distributed I/O devices (= DP slaves) prepare the sensor and actuator data on-site so that
they can be transmitted to the controller CPU via PROFIBUS DP.
ET 200iSP
Operating Instructions, 11/2017, A5E00247483-07
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