Operating Instructions Part 2

MDS 05-3624A01, Rev. B OEM Series™ I/O Guide 33
Fade Margin—The greatest tolerable reduction in average received
signal strength that is anticipated under most conditions. Provides an
allowance for reduced signal strength due to multipath, slight antenna
movement, or changing atmospheric losses. A fade margin of 20 is
usually sufficient in most systems.
Hardware Flow Control—A transceiver feature used to prevent data
buffer overruns when handling high-speed data from the RTU or PLC.
When the buffer approaches overflow, the radio drops the clear-to-send
(CTS) line, which instructs the RTU or PLC to delay further
transmission until CTS again returns to the high state.
Host Computer—The computer installed at the master station site,
which controls the collection of data from one or more remote sites.
Latency—The delay (usually expressed in milliseconds) between when
data is applied to TXD (Pin 2) at one radio, until it appears at RXD
(Pin 3) at the other radio.
MAS—Multiple Address System. A radio system where a central
master station communicates with several remote stations for the
purpose of gathering telemetry data.
Master (Station)—Radio which is connected to the host computer. It is
the point at which polling enters the network.
Multiple Address System—See MAS.
PLC—Programmable Logic Controller. A dedicated microprocessor
configured for a specific application with discrete inputs and outputs. It
can serve as a host or as an RTU.
Point-to-Multipoint System—A radio communications network or
system designed with a central control station that exchanges data with
a number of remote locations equipped with terminal equipment.
Poll—A request for data issued from the host computer (or master PLC)
to a remote radio.
Programmable Logic Controller—See PLC.
Received Signal Strength Indication—See RSSI.
Redundant Operation—A station arrangement where two transceivers
and two power supplies are available for operation, with automatic
switchover in case of a failure.
Remote (Station)—A radio in a network that communicates with an
associated master station.
Remote Terminal Unit—See RTU.