User's Manual

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 the signal strength of a number of

test packets that are exchanged between the Base and Terminal. The

higher the number, 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 or USB port. The application running on the Host Computer sends a

data prompt to the com 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 sends a new data prompt out to the

Base Station and the whole process begins again.