Siemens Simatic IPC647C Operating Instructions Manual page 235

Low-voltage directive
EC Product Safety Directive relating to the safety of products which are operated on low
voltage (50 VAC to 1000 VAC, 70 VDC to 1500 VDC) and not specified in 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 retainer
The module retainer 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 retainer for this type of module. There are also short, compact and light
modules on the market. The module retainer 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.
NEC Class 2
The "NEC", National Electrical Code, is the USA collection of regulations that generally
correspond to German VDE 0100 standards. All USA standards governing the safety of
electrical equipment and corresponding "deviations" in IEC standards are based on NEC in
terms of their country-specific requirements.
NEC Class 2 specifies higher safety requirements for protection against electric shock and
National Fire Protection Association (NFPA) requirements for fire protection. Power supplies
operating within the range from 20 VDC to 30 VDC must be equipped with an internal current
limiting circuit which safely prevents output power higher than 100 VA.
Operating system
Generic term which describes all functions for controlling and monitoring user program
execution, distribution of system resources to the user programs and the operating mode in
cooperation with the hardware (for example Windows XP Professional).
SIMATIC IPC647C
Operating Instructions, 12/2010, A5E02669337-02
Glossary
235