Glossary
SIMATIC Rack PC 840 V2
Operating Instructions, Edition 05/2006, A5E00248055-04
Glossary-5
Legacy USB support
Support of USB devices (e.g. mouse, keyboard) on the USB ports without driver.
License key
The license key represents the electronic license stamp of a license. Siemens provides the
license keys for protected software.
License key diskette
The license key diskette contains the authorizations or license keys required to enable
protected SIMATIC software.
Low-voltage directive
EC directive for product safety of products operated with low voltage (AC 50V to 1000V, DV
70V to 1500V) that are not governed by other directives. Compliance is confirmed by the CE
symbol and the EC certificate of conformity.
LPT interface
The LPT interface (Centronics interface) is a parallel interface that can be used to connect a
printer.
Memory card
Memory cards in credit card format. Memory for user programs and parameters, for
example, for programmable modules and CPs.
Module
Modules are plug-in units for PLCs, programming devices or PCs. They are available as
local modules, expansion modules, interfaces or mass storage (Mass storage module).
Module bracket
The module bracket is used to fasten modules and ensure safe contact and transport.
Shocks and vibrations especially affect large, heavy modules. It is therefore recommended
to use the module bracket for this type of module. There are also short, compact and light
modules on the market. The module bracket was not designed for these modules because
the standard fastening is sufficient for them.
Motherboard
The motherboard is the core of the computer. Here, data are processed and stored, and
interfaces and device I/Os are controlled and managed.
