GE MDS ORBIT MCR Technical Manual page 391

Hardware Flow Control: A feature used to prevent data buffer overruns when the unit is handling high-
speed data from an RTU or PLC. When the buffer approaches overflow, the unit 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.
IP: Internet Protocol
LAN: Local Area Network
LED: Light Emitting Diode
LNxxx: Orbit NIC module supporting licensed narrowband operation.
LN400: Orbit NIC module supporting licensed narrowband operation at 400 MHz.
LN900: Orbit NIC module supporting licensed narrowband operation at 900 MHz.
mA: Milliamperes
MAC: Media Access Control
Narrowband: These are channel sizes of 25KHz and down. The LN NIC module supports Licensed
Narrowband.
NIC: Network Interface Card. This is another name for the modules that are selectively included in the
product based on Orbit MCR order entry.
NX915: Orbit NIC module supporting unlicensed operation at 900 MHz.
Poll: A request for data issued from the host computer (or master PLC) to a Remote unit.
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.
PPM: Parts per Million
Programmable Logic Controller: See PLC.
Remote Terminal Unit: See RTU.
RTS: Request-to-send
RTU: Remote Terminal Unit. A data collection device installed at a Remote unit site.
RX: Abbreviation for "Receive."
SAF (Store and Forward): An available feature of the unit whereby data is stored by a designated
Remote, and then retransmitted to a station beyond the communication range of the AP.
SCADA (Supervisory Control And Data Acquisition): An overall term for the functions commonly
provided through a multiple address radio system.
SCEP (Simple Certificate Enrollment Protocol): A scalable protocol for networks based on digital
certificates, which can be requested by users without the need for assistance or manual intervention from
a system administrator.
Signal-to-Noise Ratio: See SNR.
SNR (Signal-to-Noise ratio): A measure of how well the signal is being received at a radio relative to
noise on the channel.
SSH: Secure Shell protocol for a network that allows users to open a window on a local PC and connect
to a remote PC as if they were present at the remote.
MDS 05-6632A01, Rev. F MDS Orbit MCR/ECR Technical Manual 391