Using I/Os In S7-400H; Introduction - Siemens SIMATIC S7-400H System Manual

Using I/Os in S7–400H
This section provides an overview of the different I/O installations in the S7-400H automation
system and their availability. It also provides information on configuration and programming
of the selected I/O installation.
13.1

Introduction

I/O installation types
In addition to the power supply module and CPUs, which are always redundant, the
operating system supports the following I/O installations:
Configuration
Single-channel one-sided
Single-channel switched
System redundant
Dual-channel redundant
A dual-channel redundant configuration at user level is also possible. You nevertheless need
to implement the high availability in the user program (see section Other options for
connecting redundant I/Os (Page 207)).
Addressing
No matter whether you are using a single-channel one-sided or switched I/O, you always
access the I/O via the same address.
Limits of I/O configuration
If there are insufficient slots in the central racks, you can add up to 20 expansion units to the
S7-400H configuration.
Module racks with even numbers are always assigned to central rack 0, and racks with odd
numbers are always assigned to central rack 1.
For applications with distributed I/O, each of the subsystems supports the connection of up
to 12 DP master systems (2 DP master systems on the integrated interfaces of the CPU and
10 via external DP master systems).
The integrated MPI/DP interface supports the operation of up to 32 slaves. You can connect
up to 125 distributed I/O devices to the integrated DP master interface and to the external
DP master systems.
S7-400H
System Manual, 03/2012, A5E00267695-11
Availability
normal
enhanced
enhanced
high
13
169