Siemens SIMATIC S7-400 Configuration And Use Manual page 19

Uniform Displays
The following applies to the status and error displays of the S7-400:
• Identical errors are always displayed in the same way.
• Identical displays are always located at the same location on the front of the
module.
• The meaning of flash frequencies is always the same.
To summarize, once you understand the display principle of one module, you can
interpret the displays of all other modules.
MPI/DP Interface
All CPUs feature an integrated interface with multi-point capability (MPI).
The MPI interfacce is used for the following tasks:
• Programming and parameter assignment
• Operator control and monitoring
• Configuring simple network structures between CPUs
S7-300 and S7-400 CPUs exchange data via the MPI interface using a variety
of communication functions.
Using this interface as a DP interface and the CPU as a DP master, you can
operate up to 32 DP slaves.
Profibus DP Interface
Except for the CPU 412-1, all CPUs feature at least one other interface for
connecting to Profibus DP in addition to the MPI/DP interface.
The Profibus DP interfacce is used for the following tasks:
• The CPU acts as the DP master to accees all stations on the Profibus DP.
• The CPU itself is a DP slave on a DP interface.
You can equip CPUs 41x-3 and 41x-4 with interface modules to provide additional
DP interfaces.
I/O Expansion
Any CPU can be used in the S7-400 product range.
Password Protection
You can assign three levels of access rights for CPUs from the programming
device in STEP 7. To assign a protection level, you specify a password, which has
to be entered before unrestricted access to a "protected" CPU is allowed.
Table 2-1 shows an example of a selection of CPU functions and how they are
assigned to the various levels of protection.
Automation System S7-400 Configuration and Use
A5E00442711-02
CPUs of the S7-400
2-3