Siemens SIMATIC S5 Manual page 315

Glossary
Process image
PROFIBUS
PROFIBUS-DP
Reaction time
Redundancy
Redundant remote
operation
Reference
potential
Response
monitoring
Glossary-8
A process image of all inputs (= PII) or all outputs (= PIO) at a given time.
You can access the process image in the control program.
PROcess FIeld BUS, German process and field bus standard defined in the
PROFIBUS standard (DIN 19245).
The standard defines functional, electric and mechanical characteristics for a
bit-serial field bus system.
PROFIBUS-DP draft standard (DIN 19245, Part 3), on which the ET 200
distributed I/O system is based.
The primary function of PROFIBUS-DP is to sustain the high-speed cyclic
exchange of data between the central DP master and the distributed I/O
stations.
The reaction time is the average time which elapses between the change of
an input and the corresponding change of an output.
The provision of duplicates for the sake of reliability. If one component fails
the duplicate assumes the role of the original.
The duplication of a bus line monitored at both ends by two 485 repeaters in
remote mode:
Potential to which the voltages of the circuits are referenced and the datum
for measurement of these voltages.
A slave parameter in COM ET 200 Windows. If a DP slave is not addressed
within the response monitoring time, it goes to safe condition, i.e. the DP
slave sets its output to "0".
Response monitoring can be switched on or off for each individual DP slave.
R R R
Remote segment
(redundant segment)
R R R
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a