User's Manual

3-1
Chapter 3
Operational Theory
Before you jump in and start writing a complex host program, it might be nice to
be familiar with the theory behind the operation of your RF Terminal. The RF
Terminal has three different modes of communication:
• Two-Way Mode - the host program transmits requests for data to
the terminal via the Base Station. The RF Terminal transmits a
response back to the Base Station, which in turn sends the data on to
the host program. This is a truly interactive mode allowing you to
create flexible programs for a variety of applications that are
computer led and controlled.
• One-Way Mode - the RF Terminal transmits to the host with only
confirmation from the Base Station. The host program receives data
from the Base Station as it would any other serial device. The host
cannot send data to the terminal; it can only receive information.
• Site Test Mode – the Base Station and RF Terminal work together
to evaluate the site and determine the best location for the Base
Station. The site test evaluates the percentage of successful
transmissions on the first and second tries from any given area. The
higher the percentage, the more successful your communications
will be from that area. This helps you to identify problem areas
before you implement your RF Terminal system. At 30 ft., this is
also the acid test for suspected bad radios in a base or in a terminal.
Let’s start with a discussion of the basic theory behind a Two-Way RF Terminal
system.
How the Two-Way RF System works
Basic RF System communications…
The RF system consists of three components – Host Computer, Base Station and
RF Terminal. The Base Station connects to the Host Computer via the serial
port. The application running on the Host Computer sends a data prompt to the
serial port where the Base Station receives it. The Base Station then transmits
the data prompt via radio frequency to the intended RF Terminal. The RF
Terminal displays the data prompt on the display and waits for the operator to
enter the requested data. Once the operator enters his data, the RF Terminal
transmits the data to the Base Station, which in turn passes it on to the Host
Computer. The application on the host computer processes the information and