Worth Data 701 RF manual Operational Theory, How the Two-Way RF System works

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-WayRF 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 com- puter processes the information and sends a new data prompt out to the Base Station and the whole process begins again.

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