Single Operation; Reasons For Single Operation - Siemens SIMATIC S7-400H Manual

Single Operation

Overview
This appendix gives you the information you need for single operation of a
fault-tolerant CPU (CPU 414-4H or CPU 417-4H). You will learn in the following
• how single operation is defined
• when single operation is necessary
• what you have to take into account with single operation
• how the fault tolerant-specific LEDs respond
• how to configure a fault-tolerant CPU for single operation
• how you can expand it to form a fault-tolerant system
The differences compared to a standard S7-400 CPU that you have to take into
account when configuring and programming the fault-tolerant CPU are contained in
Appendix D.
Definition
By single operation, we understand use of a fault-tolerant CPU in a standard
SIMATIC-400 station.

Reasons for single operation

The following applications are only possible with a fault-tolerant CPU. In other
words, they are not possible with standard CPUs in the S7-400 range.
• Use of fault-tolerant connections
• Configuration of the S7-400F fail-safe programmable logic controller
A fail-safe user program can only be compiled as being executable if the
fault-tolerant CPU is used with a fail-safe runtime license (for more information
refer to the manual S7-400F and S7-400FH Programmable Controllers.).
Note
The fault-tolerant CPU self-test can also be performed in single operation.
Automation System S7-400H Fault-tolerant Systems
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