Siemens SIMATIC S7-300 Series Reference Manual page 171

Glossary
Accumulator
Accumulators are registers in the ³ CPU. They are an intermediate memory for
loading, transfer, compare, calculation and conversion operations.
Address
An address is an ID for a specific operand or operand area, for example: Input I
12.1; memory word MW 25, data block DB 3).
Analog module
Analog modules convert process values (e.g. temperature) into digital values, so
that they can be processed by the central processing unit, or convert digital
values into analog manipulated variables.
Automation system
An SIMATIC S7 automation system is a ³ programmable logic controller.
Backplane bus
The backplane bus is a serial data bus over which the modules communicate
and over which the necessary power is supplied to the modules. The connection
between the modules is established by bus connectors.
Backup battery
The backup battery ensures that the³ user program in the ³ CPU is saved in
the event of a power failure and that defined data areas, memory bits, timers and
counters are retentive.
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
Glossary-1