Glossary
Windows Automation Center, WinAC Slot Version 4.0
Hardware Installation and Operating Manual, Edition 02/2006, A5E00273194-02
179
PLC:
-> Programmable logic controller
Process image:
The process image is an integral part of the system memory of the S7-400CPU.
The signal states of the input modules are written into the process-imageinput table
at the start of the cyclic program. At the end of the cyclic program, thesignal states
in the process-image output table are transferred to the outputmodules.
PROFIBUS:
Physical communications layer that can be used for PROFIBUS DP
communications to I/O orS7 communications to STEP 7, S7 CPUs, and S7
applications.
PROFIBUS DP:
Using PROFIBUS-DP, you can set up a distributed I/O system. Digital and
analogmodules are transferred by the automation system to the process on site –
andover a distance of up to 23 km at that (when using fiber–optic cables). The
digital and analog modules are connected to the automation system via
thePROFIBUS-DP fieldbus and addressed in the same way as centralized I/O.
PROFIBUS-DP conforms to the standard EN 50 170 Volume 2, PROFIBUS.
Programmable logic controller:
Programmable logic controllers (PLCs) are electronic controllers whose function
issaved as a program in the control unit. The configuration and wiring of the
devicetherefore do not depend on the function of the controller. The programmable
logiccontroller has the architecture of a computer; it consists of -> CPU with
memory,I/O modules and internal bus system. The I/O and the programming
language aredesigned to meet the control engineering requirements.
Programming device:
Programming devices are essentially personal computers which are
compact,portable and suitable for industrial applications. They are equipped with
specialhardware and software for SIMATIC programmable controllers.
RAM:
A RAM (random access memory) is a semiconductor with random access.
RESTART:
RESTART mode is activated on a transition from STOP mode to RUN mode. It can
be initiated by the mode selector switch, after a Power On, or through an operator
input on the programming device.
