Users Manual

136 MDS™ Master Station MDS 05-6399A01, Rev. G

slight antenna movement or changing atmospheric losses. A fade margin of 20 to 30 dB is usu-

ally sufficient in most systems.

FPGA—Field Programmable Gate Array.

Frame—A segment of data that adheres to a specific data protocol and contains definite start

and end points. It provides a method of synchronizing transmissions.

Gate—An operating mode of the transceiver with respect to diagnostic/management activities.

See also NODE, PEER, and ROOT.

Hardware Flow Control—A transceiver feature used to prevent data buffer overruns when han-

dling 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 unit, which controls the collection of

data from one or more remote sites.

I/O—Input/Output.

IP—Internet Protocol.

Intrusive Diagnostics—A mode of remote diagnostics that queries and commands radios in a net-

work with an impact on the delivery of the system “payload” data. See Active messaging.

LAN—Local Area Network.

LED—Light Emitting Diode.

Latency—The delay (usually expressed in milliseconds) between when data is applied to the

TXD pin at one radio, until it appears at the RXD pin of another radio.

Listen Before Transmit—A collision avoidance mechanism that attempts to allow transmission

only when the channel is clear.

mA—Milliamperes (current flow). 1000 mA = 1 Ampere.

MAC—Media Access Control.

NIC: Network Interface Card. This is another name for the modules that are selectively included

in the product based on order entry.

NX915: A GE MDS NIC module supporting unlicensed operation at 900 MHz

MAS—Multiple Address System. A radio system where a central master unit 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 poll-

ing enters the network.

Multiple Address System—See MAS.

Network-Wide Diagnostics—An advanced method of controlling and interrogating GE MDS

radios in a radio network.

Node—An operating mode of the transceiver with respect to diagnostic/management activities.