Z Technology, Inc.

R500 Series

Quick Basic

Control Software

Application note

By the

Setting up the System

Introduction

Many features of the R-500 series field strength meter are accessible through the RS-232 serial communication port. Use of the RS-232 port along with a personal computer (PC) allows operation of the instrument via computer programs or directly from the PC keyboard.

Several control software programs are provided which can be used to control the field strength meter with a computer. The purpose of this application note is to help the R-500 series operator effectively use the R-500 Series Quick Basic Control Software Disk made available by Z Technology.

Computer

To remotely control the R-500 series field strength meter a "controller" is necessary. Any computing device with the ability to transmit and receive the necessary RS-232 communications can control the instrument. For the purpose of this application note, the controller recommended to run the supplied programs is an IBM compatible personal computer.

Software

The examples described herein were written using the high level programming language QBASIC. It is a universal language and is distributed with MSDOS version 6.2 and earlier. This language includes RS-232 communication capabilities. QBASIC is an interpretive language meaning the QBASIC interpreter interprets a line of source code at a time while running. To make executable files Microsoft QUICK BASIC ver 4.5 is used.

Interconnecting Cables

The PC must have one of its serial ports correctly connected to the R-500 series field strength meter. Proper connections are assured if you use the standard "straight through" RS-232 cable provided with the meter. The standard "straight through" RS-232 cable has a DB9 male connector on one end and DB9 female connector or the other end. If your PC is equipped with only a DB25 male connector serial port, use a DB25 female to DB9 male adapter available from your local computer supplier. For reference in building a custom cable below is a pinout of the R-500 Series DB9 Female Connector.

For proper communications between R-500 series meter and computer, the communications parameters between the meter and your PC must match. The Factory default R-500 Series meter parameters are set as follows:

Setting the computer's communications parameters: The computer's baud rate, number of data bits, type of parity, number of stop bits and remote address must match those of the R-500 Series meter (Baud rate, 8,N,1 and remote address).

R-500 Series meter data bits, stop bits, and parity parameters cannot be changed, the computer's must be set to match those of the instrument. The baud rate and remote address parameters must be set to the same value for both instrument and PC.

Changing the R-500 Series meter's baud rate and remote address: The meter can be set to operate at 1200, 2400, or 9600 baud. Usually, you will want to use the highest baud rate to minimize communications time between the meter and the computer. The remote address can be set to any number between 0 and 255, 1 is the factory default.

The FUNCtion to set baud rate and to set remote address are "locked out" to prevent accidental changes. To access and change them:

To unlock the control functions:

1. Press the FUNCtion button on the front panel, then use the TUNE-Knob to select "F59".

2. Press the TUNE-Knob -- the meter will immediately return to its previous operating mode.

3. Repeat steps 1 and 2 two more times. Function "F59" has now been consecutively selected three times; therefore, the baud rate and remote address functions are unlocked.

To change the baud rate or remote address:

1. Use the FUNCtion button and TUNE-Knob to select function "F43" to change the baud rate or select function "F44" to change the remote address. When you press the TUNE-Knob, the present value will be displayed on the large right LCD. To change it, rotate the TUNE-Knob until the desired value is displayed and press the TUNE-Knob to store the new setting. Press the FUNCtion button to exit the setup function.

Z Technology provides with each meter a 3.5" floppy disk containing several Quick Basic programs. They can be used as is, or as examples of how to control the R-500 Series meter through the serial port. Programs range from simple to the complex. Each program demonstrates a unique method of data collection. Some programs were written for specific measurement requirements. Users with similar requirements may find these programs useful, just as written. For those users with unique requirements, these programs will be useful as a starting point in developing your own custom programs.

If you choose to develop your own custom program, it is suggested refer to the Creating Custom Software section later in this application note, and study the STAT.BAS program on the Control Software disk. STAT.BAS is the simplest of all the programs, it has no error checking and uses just one simple command, so it is the easiest to follow. Once you have an understanding of STAT.BAS, you are ready to look at one of the more complex programs. SINGLE.BAS is a good next step. By analyzing these programs, an experienced programmer will quickly understand the communication protocols and the steps required to develop custom programs.

Programs residing on the Quick Basic Control Software disk are presented in both .BAS (basic) and .EXE (executable) formats. At the time this programs note is being written, the following programs are available:

MENU
MEAS_NOW
SINGLE
SCAN
FILE_CTL
STAT

Descriptions of these programs are in the next section of this application note.

All Quick Basic Control Software run in the DOS environment. If you have the Windows operating system, we recommend completely exiting Windows before running a program. (Use of the Program Manager, MSDOS Prompt icon to get to DOS is not recommended, it sometimes causes erratic behavior due to the non real-time nature of the Windows operating system which would still be running.)

Files that end in .BAS must be run from QBASIC. QBASIC is provided with MSDOS version 6.2 or earlier. Those with a .EXE ending are run by simply typing the file name after the DOS C:> prompt.

Each Control program begins with a short description screen. User instructions and requests for necessary input parameters will be displayed before the measurement begins.

This application note reviews each program and gives a brief report of its use.

MENU.BAS and MENU.EXE

This program in both .BAS and .EXE form is included for several reasons. It provides a defacto index of useful Commands for controlling the R-500 Series meters and gives the user an easy way to exercise each command. Since all important Commands are presented in this program, it provides a good set of examples for those developing there own custom programs.

A very useful function of this program is in revising Setup parameters for the R-500 Series meter. Timing parameters can be set or modified and the instrument's Data Logging capability enabled and disabled.

The program begins by displaying instructions for connecting the R-500 series meter to a PC. The PC screen is shown in the box below.

After the meter is correctly connected to the PC, press the ENTER ("Return") key.

A new set of text is displayed as a reminder of meters normal settings for Address and Baud rate. These two parameters must then be chosen for this session. Finally you are asked to identify the communications or serial port being used by the PC to interface with your R-500 Series meter. Notice the defaults in square brackets match the meter factory defaults.

Follow the directions of the last line or type in a number corresponding to its associated command then press ENTER. Entering "X" exits the programs.

To Setup special R-500 Series meter parameters enter "S". This option allows the user to tailor three (3) different types of instrument settings:

1. Delays before and between signal measurements.
2. Number of signal measurements taken which are averaged and sent to the RS-232 port or the LCD display.
3. Data Logging Enabled/Disabled.

The following screen appears on the PC:

Enter A,B,C, or D to change the corresponding parameter.

When "B", 1888, is set to 01 Resident Data Logging is enabled. On the R-505 only, while set to 01 (enabled), the RS-232 port communication has approximately 500 msec added to every serial port command or exchange. When 1888 is set to 00 (disabled) Resident Data Logging is not possible; however, in this mode serial communication speed is increased dramatically since the above mentioned 500msec is eliminated. It is our experience that most users are concerned with RS-232 port speed. Since this is the case, the standard R-505 is shipped with Resident Data Logging disabled. That is, at the factory, 1888 is loaded with 00. (The following timing values assume 1888 is set to 00 on the R-505).

Note: Certain highlighted main-menu functions set features that can be used only in the Data Logging Mode. The functions in this category are 3, 4, 5, 6, 13, 14, 15 and 16. These items are active, only when address 1888 it set to 01.

"D", 18AB, sets the number of "readings" which are averaged before a "measurement" is sent to the serial port or the front panel. In order to increase meter measurement accuracy, multiple readings are recommended. The instrument is normally calibrated with this parameter set to 04. In that case, a "measurement" is the averaged of four (4) "readings".

All Data (for all addresses) must be entered in Hex. For instance, to have a measurement be the average of 15 readings, enter the Hex value "0F".

"A", 1880, and "C", 18AA, are used to set delays between "readings" (A) or between groups of "measurements" (C).

An example will help to understand the sequence of these values. When 1880, 18AA and 18AB are set at the above default values, four (4) "readings" will be taken, with 10msec of delay between each reading, and a delay of 24.6 msec is added between each group of four "readings". In addition to these delays, a normal system delay of approximately 150msec is inherent in the instrument. Below is a diagram of "measurement" cycle time.

When the delay and number of signal readings are set as shown, the total time between serial port measurements will be approximately 205 msec.

This program performs a field strength measurement at a specified frequency on command. The time is recorded and a "Comments" field is provided for recording notes after each measurement.

The first screen display is shown above. The second, third and fourth are presented below.

Respond with F, R, Q, or RETURN. A RETURN command immediately begins the measurement routine. Choosing F will clear the screen and create the following message:

Enter a file name of your choice where measured data is to be stored -- or --
Enter "DIR" to display all files and directories on the current disk.
Enter "CD" to choose one of these existing Directories.
Enter "MD" to set up a new Directory.

When this step is finished, the program begins the measurement routine. Information is displayed on the screen and recorded to the named file. A sample of the display with the Comment field utilized follows:

This program takes measurements at one frequency. The measured signal levels are displayed on the PC screen and can be saved in a file.

The following information is displayed when run:

If the user responds with the letter "F" the program displays:

If the [ENTER] key is selected rather than the letter "F", the program will begin repeatedly to command the meter to take signal level measurements and display them along with the time. If a file or directory was chosen, the measurements will be displayed on screen and also recorded to the named file. Any key stroke stops the process.

Select ENTER to start the program and to display information to the PC screen. Select "F" to display information and save to a file of your choice. (See detailed description above). The screen which follows used a start frequency = 88.3 MHz, frequency step size = 200 KHz and number of steps=12.

Enter "2" to run an existing measurement sequence which you have previously created. To create a new sequence, enter "1". The user is lead through a series of steps accessed via a menu which displays the following:

This program is a very simple example intended to help the programmer get started creating custom programs for the R-500 Series meter.

The screens for the STAT program are shown below.

After the meter responds to the Report Status command control returns to the DOS prompt.

STAT.BAS uses the meter Command 29 to "Report the status of the meter". It provides a good example of the meters send and receive communication packet structure. As well as demonstrating how these structures can be implemented in a group of reusable sub-programs. The structure of this example is the basis of all the programs on the Quick Basic Control Software disk.

Bit	Status
0	Always "0"
1	Unable to perform last command
2	Unsuccessful read/write to EEPROM
3	Data log timer needs to be reprogrammed
4	Data log timer has expired
5	Not used
6	Not used
7	Not used

Meter's remote address: default = "1" (0000 0001)

Packet size: Total number of bytes being sent.

Command Echo: Command being responded to.

Data bytes: Data (from 0 to 16 bytes) as required by the command being sent.

Packet Checksum: The logical compliment of an 8-bit sum of all bytes in the packet excluding the checksum byte.