Siemens SIMATIC S7-300 Quick Start Manual page 75

Glossary
A
Address
An address is part of a STEP 7 statement and specifies what the processor
should execute the instruction on. Addresses can be absolute or symbolic.
Automation An automation system is a programmable logic controller (PLC) in the case
System of SIMATIC S7, a SIMATIC C7 control system (PLC with integrated
operator panel), or a SIMATIC M7 automation computer.
B
Backplane Bus
The backplane bus of a SIMATIC S7 programmable logic controller supplies
the plugged-in modules with the internal operating voltage and enables data
exchange between modules. In the S7-400, the backplane bus is divided into
the I/O bus (P bus) and the communication bus (C bus). In the S7-300, the
backplane bus has a modular design in the form of U rails that each connect
two modules with each other.
Block
Blocks are part of the user program and can be distinguished by their
function, their structure, or their purpose. STEP 7 provides the following
types of blocks:
Primer: S7-300 Programmable Controller, Quick Start
C79000-G7076-C500-01
Logic blocks (FB, FC, OB, SFB, SFC)
Data blocks (DB, SDB)
User-defined data types (UDT)
Glossary-1