Siemens SIMATIC S7-300 Hardware And Installation Manual page 245

Parameters
1. Variable of a STEP 7 code block
2. Variable for declaring module response (one or several per module). All modules
have a suitable basic factory setting which can be customized inSTEP 7.
There are --> static parameters and --> dynamic parameters
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.
PG
--> Programming Device
Equipotential bonding
Electrical connection (equipotential bonding conductor) which gives the bodies of
electrical equipment and external conducting bodies the same or approximately the
same potential, in order to prevent disturbing or dangerous voltages from being
generated between these bodies.
Non-isolated
The reference potential of the control and on-load power circuits for non-isolated
I/Os is electrically interconnected.
Electrically isolated
The reference potential of the control and on-load power circuits for isolated I/Os is
electrically isolated; e.g. by optocouplers, relay contact or transformer. I/O circuits
can be connected to a common potential.
Priority class
The S7 CPU operating system provides up to 26 priority classes (or "Program
execution levels"). Specific OBs are assigned to these classes. The priority classes
determine which OBs interrupt other OBs. If a priority class includes several OBs,
they do not interrupt each other, but are executed sequentially.
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02
Glossary
13-11