Siemens Simatic S7-300, Руководство по аппаратному обеспечению и установке, Страница: 230 / 242

Glossary
S7-300 Programmable Controller Hardware and Installation
12-10
A5E00105492-01
OB priority
The CPU --> operating system distinguishes between different priority classes, e.g.
cyclic program execution, program execution controlled by process interrupt. Each
priority class is assigned --> organization blocks (OBs) in which the S7 user can
program a response. The OBs have different standard priorities which determine
the order in which they are executed or interrupted in the event that they are
activated simultaneously.
Operating mode
SIMATIC S7 PLC operating modes are: STOP, --> START-UP, RUN.
Operating system of the CPU
The operating system of the CPU organizes all functions and processes of the
CPU which are not associated with a special control task.
Organization Blocks
Organization blocks (OBs) represent the interface between the operating system of
the CPU and the user program. The processing sequence of the user program is
defined in the organization blocks.
Parameters, dynamic
Unlike static parameters, dynamic parameters of modules can be changed during
operation by calling an SFC in the user program, for example limit values of an
analog signal input module.
Parameters, static
Unlike dynamic parameters, static parameters of modules cannot be changed by
the user program, but rather by changing the configuration in STEP 7, for example
the input delay on a digital signal input module.
Parameters
1. Variable of a STEP 7 code block
2. Variable for declaring module response (one or several per module).
All modules are delivered with a suitable factory setting which can be changed in
the configuration withSTEP 7.
There are --> static parameters and --> dynamic parameters
PG
--> Programming Device