9 Appendix
9.3 Glossary
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XI/ON: XNE-GWBR-2ETH-IP
09/2011 MN05002007Z-EN
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Mass
All interconnected inactive components that do not take on a dangerous touch potential in the case of a
fault.
Master
Station in a bus system that controls the communication between the other stations.
Modbus TCP
The Modbus protocol is part of the TCP/IP protocol.
The communication is realized via function codes, which are implemented into the data telegram.
Modbus TCP uses the Transport Control Protocol (TCP) for the transmission of the Modbus user protocol
in Ethernet-TCP-IP networks.
Module bus
The module bus is the internal bus in a XI/ON station. The XI/ON modules communicate with the
gateway via the module bus which is independent of the fieldbus.
MSB
Most Significant bit
Ping
Implementation of an echo-protocol, used for testing whether a particular host is operating properly and
is reachable on the network from the testing host.
PLC
Programmable Logic Controller.
Potential compensation
The alignment of electrical levels of electrical components and external conductive components by
means of an electrical connection.
Potential free
Galvanic isolation of the reference potentials in I/O-modules of the control and load circuits.
Potential linked
Electrical connection of the reference potentials in I/O-modules of the control and load circuits.
Protective earth
Electrical conductor for protection against dangerous shock currents. Generally represented by PE
(protective earth).
Radiation coupling
A radiation coupling appears when an electromagnetic wave hits a conductive structure. Voltages and
currents are induced by the collision. Typical sources of interference are for example, sparking gaps
(spark plugs, commutators from electric motors) and transmitters (e. g. radio), that are operated near to
conducting structures.
Reaction time
The time required in a bus system between a reading operation being sent and the receipt of an answer.
It is the time required by an input module to change a signal at its input until the signal is sent to the bus
system.
Reference potential
Potential from which all voltages of connected circuits are viewed and/or measured.
Repeater
Amplifier for signals transmitted via a bus.
