15 Glossary of Terms
Netmask:
Groups stations to a Net
The AND-operation between the IP Address and the Mask is an important value. When to
stations have the same result and the same mask, they are "in the same net". Which means
they can communicate direct, without transmitting to a Router.
PAT:
Port Address Translation
A technique to share a public IP Address by many internal servers on private addresses. The
target address and port is replaced with values stored in an internal table. Mostly used
together with NAT.
Router:
Transmits data over the Internet
The backbone devices of the Internet. Routers connect two networks together. On one side
they receive data frames containing IP-data. They extract these data, and send them on
another side; there also stored in data frames of the second network. Typically they connect
more than two networks. The basic task is to decide which route the IP-data must take now.
RS232/V.24:
common serial transmission
Characters are sent as separate bits, timing is well defined. The medium is copper cable,
using t/- 12 Volt. Each signal is defined related to a common ground; one wire per
signal plus GND. RS 232 is a point-to-point connection.
RS422/V.11:
Industrial serial transmission (multidrop)
A transmission method with balanced signals. Designed for higher speed, longer cables and is
resistive against electrical noise. RS 422 allows for up to 16 receivers. The typical transmission
is via twisted pair copper cable using balanced signals. Sender and receivers must share a
common voltage range (max. +/-7 Volt difference). Two lines per signal, plus common GND.
RS 422 is a point-to-multipoint connection.
RS485:
Industrial serial transmission (multipoint)
The signals and cables are the same as RS 422. The transmitters can go tri-state. Several
stations can send data on the same lines, at different times.
RS 485 is a multipoint-to-
multipoint connection.
SNMP:
Simple Network Management Protocol
A general purpose configuration system. Devices understanding SNMP may be configured
and monitored.
TCP/IP:
Transmission Control Program/Internet Protocol
TCP establishes connections between two partners via the Internet. The data is sent in IP-
frames, each frame is acknowledged be the recipient. Lost packages are repeated. Software
using TCP has a secured transmission; the delivery of the data is guaranteed.
TKIP:
Temporal Key Integrity Protocol
An encryption scheme for Wireless LAN. It was developed from the WEP. The key used for
encryption is changed while data is transmitted. An attacker will not get enough data with
the same key to break the code.
UDP:
User datagram protocol
Similar to TCP the data is sent in IP-frames. But in opposite there is no connection or
acknowledge by the recipient. The transmission is faster for small data, but data can get lost.
Software using UDP must handle the related problems.
September 2016
NetCom Plus User Manual
130
Summary of Contents for NetCom Plus 111
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