Siemens SIMATIC ET 200S Manual page 561

Process image
The process image is a component of the system memory of the DP master. The
signal states of the input modules are transferred to the process-image input area
at the beginning of the cyclic program. At the end of the cyclic program, the values
of the process-image output area are transferred to the DP slave as the signal
states.
Process-related modules
Modules that are equipped with technological functions, such as counting pulses,
positioning, and controlling stepping motor power units.
PROFIBUS
PROcess FIeld BUS, a German process and field bus standard defined in
IEC 61784-1:2002 Ed1 CP 3/1. It defines the functional, electrical, and mechanical
properties of a bit-serial field bus system.
PROFIBUS is available with the protocols DP (which stands for distributed
peripherals, that is, distributed or remote I/O), FMS (which stands for field bus
message specification), PA (= process automation), or TF (= technology
functions).
PROFIBUS address
Each bus node must receive a PROFIBUS address to identify it uniquely on the
PROFIBUS.
The PC/programming device has the PROFIBUS address "0".
The PROFIBUS addresses 1 to 125 are permitted for the ET 200S distributed I/O
system.
Programmable controller
A programmable logic controller consisting of at least one CPU, various input and
output modules, and operator interfaces.
• A protective ground bar
• Additionally required voltage
Reference potential
Potential from which the voltages of the circuits involved can be observed and/or
measured.
Reversing starter
A reversing starter is a ³ motor starter that determines the direction of rotation of
a motor. It consists of a circuit breaker and two contactors.
ET 200S Distributed I/O System
EWA-4NEB780602402-09
Glossary
Glossary-5