Glossary
ET 200S
Manual, Edition 10/2005, A5E00514527-01
Glossary-7
Provider-consumer principle
Unlike PROFIBUS DP, both partners on PROFINET IO are independent providers for
transmission of data.
Real time
Real time means that a system processes external events within a defined time.
Determinism means that a system responds in a predictable (deterministic) manner.
Both requirements are important for industrial networks. PROFINET satisfies these
requirements. Thus, as a deterministic real-time network, PROFINET is designed as follows:
• The transfer of time-critical data between different stations via a network is guaranteed
within a defined interval of time.
• To this end, PROFINET has an optimized communication channel for real-time
communication: Real time (RT).
• The time of transfer can be accurately determined.
• It is ensured that seamless communication can take place in the same network by means
of other standard protocols, such as industrial communication for PG/PC.
Reference data companions
A value is assigned to every peripheral module in the input or output data telegram which
gives evidence about the quality of this reference date. For example outputs of a module can
thus be switched off without influencing other modules.
Reference potential
Potential from which the voltages of the circuits involved can be observed and/or measured.
Reversing starter
A reversing starter is a → motor starter that determines the direction of rotation of a motor. It
consists of a circuit breaker and two contactors.
Segment
The bus line between two terminating resistors forms a segment. A segment contains 0 to 32
→ bus nodes. Segments can be interconnected by means of RS 485 repeaters.
SELV
Safety Extra Low Voltage
Slave
A slave can only exchange data with a → master when requested by it to do so. By slaves we
mean, for example, all DP slaves such as ET 200X, ET 200M, ET 200S, etc.
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