Communication - Siemens SIMATIC S7-300 Hardware And Installation Manual

Glossary
PLC
--> Programmable controller
STEP 7
Programming language for developing user programs for SIMATIC S7 PLCs.
System diagnostics
System diagnostics is the term used to describe the detection, evaluation and
signaling of errors which occur within the programmable controller. Examples of
such errors are program errors or module failures. System errors can be displayed
with LED indicators or in STEP 7.
System function
A system function (SFC) is a -->function integrated in the operating system of the
CPU that can be called, as required, in the STEP 7 user program.
System function block
A System Function Block (SFB) is a --> function block integrated in the CPU
operating system. If required, it can be called in the STEP 7 user program.
System Memory
The system memory (RAM) is integrated on the central processing unit. System
memory contains the operand areas (e.g. timers, counters, memory bits) and the
data areas required internally by the --> operating system (e.g. buffers for

communication).

System status list
The system status list contains data describing the current status of an S7-300.
You can use it to gain an overview of the following at any time:
• The S7-300 configuration
• The current CPU configuration and the configurable signal modules
• Current status and processes in the CPU and configurable signal modules.
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S7-300 Programmable Controller Hardware and Installation
A5E00105492-02