Characteristics Of An I-Device - Siemens SIMATIC ET 200AL System Manual

Functions
5.2 Intelligent IO devices (I-devices)
5.2.3

Characteristics of an I-Device

Principle
An I-device is included in an IO system like a standard IO device.
I-device without lower-level PROFINET IO system
The I-device does not have its own distributed I/O. The configuration and parameter
assignment of the I-devices in the role of an IO device is the same as for a distributed I/O
system (for example ET 200).
Figure 5-7
I-device with lower-level PROFINET IO system
Depending on the configuration, an I-device can also be an IO controller on a PROFINET
interface in addition to having the role of an IO device.
This means that the I-device can be part of a higher-level IO system via its PROFINET
interface and as an IO controller can support its own lower-level IO system.
The lower-level IO system can, in turn, contain I-devices (see figure below). This makes
hierarchically structured IO systems possible.
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I-device without lower-level PROFINET IO system
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH