Siemens SIMATIC S7-400 Installation Manual page 209

Glossary
A
Address
An address is the identifier for a specific area of memory on which an instruction
acts.
Examples: Input I 12.1; Memory Word MW24; Data Block DB3.
Analog Module
Analog modules convert analog process variables (for example, temperature) into
digital values that can be processed in the CPU or they convert digital values into
analog manipulated variables.
B
Backup Battery
The backup battery ensures that the user program in the CPU is not lost in the
event of a power failure and that defined data areas, bit memory, timers, and
counters are also retained.
Bit Memory (M)
A memory area in the system memory of a SIMATIC CPU. This area can be
accessed using write or read access (bit, byte, word, and double word). The bit
memory area can be used by the user to store intermediate results. It can be
accessed bit by bit, byte by byte, word by word, or double word by double word.
Building Ground
The connection between data processing equipment and ground, whereby no
unacceptable functional interference to data processing equipment is caused by
external effects, such as interference caused by power systems. The connection
must be in the form of a low-noise ground.
Bus segment
Entity of a serial bus system, coupled via repeaters.
Automation System S7-400 Hardware and Installation
A5E00850741-01
Glossary-1