This is a testprogram for the RS232 interface.
When you connect a null modem cable to another computer or make a connection with a microcontroller-board with a RS232 connector, you can test the connection and exchange data.
When a PC is connected to a microcontroller, a robot for instance,then the big problem is: what is happening between the two? At a very basic level you can inspect the RS232-buffer in the PC to see what the robot did send to the computer. Every byte will be visible. Furthermore it is possible to send small commands - as bytelists - to the robot to let him do something like making a sound or putting a led on. These things were the reason for making this program.
It does not matter how you program the microcontroller or which language you use there - C, Bascom or whatever - if sending bytes to the microcomputer is possible, you are in business.
But perhaps the most important thing is to make it possible for Visual Prolog to communicate directly with a robot. If it is your goal to let the robot do smart things by using Visual Prolog doiing the hard work then here is your chance. For that purpose you can use the packages from this program.
For computers to be connected you need a nullmodem cable. There is no "standard" nullmodemcable. I used three wires: pin 2 and 3 crossed and pin 5 (ground ) on DB9 connectors. That's all. It will be clear that there is no hardware handshaking in such case.
For connecting to a robot a normal RS232cable is enough.
After compiling the program choose a communication port with Start from the menu. The program displays the comports it can find in the registry.
What you see then is the status of the communication port. At this particular moment no initialisation has taken place by this program. What you see is exactly what Windows or some communicationprogram has left behind. The reason for this will be clear in a moment.
When the program starts up it reads out all the communication parameters and preserves them in an internal database. It is this database you see. You find all facts in the tabcontrol under parameters. But it is not possible to change them there. This database can be saved and loaded. To really understand the content you have to study all about communication resources in the platformSDK for Windows.
Do not expect that you already can communicate with another apparatus.
Let us presume that two computers are connected with a nullcable and that you started up as described above. There is no garantee that the communication parameters on both machines are the same, even if you do not see that at first glance.
There are two ways to initialize the connection:
If none of this methods work you are on your own.
If you connect a computer to a microcontroller-board (say a robot) then consider the computer as master and the robot as slave. Therefore you should initialize this program first. The code on the microcontroller-side is your own responsibility.
Choose text- or decimal/hexadecimal notation.
In textnotation type a normal text.
54 67 0 0xFF 255 0x0A
then the messagewindow will produce in binary-hexadecimal notation
You will notice that the unicodecharacters are converted to bytevalues.
If you used decimal/hexadecimal notation is and typed
54 67 0 0xFF 255 0x0A
you will read this in the messagewindow
If another device sends data to your computer you will not see anything at first. When you push the readbutton the program reads the buffer and writes a number of bytes to the messagewindow in the same binary-representation as above. You can change the number of bytes that will be read from the buffer each time you push the readbutton. If you see only zero's like
then the buffer is empty.
Do not send an uninterrupted stream of bytes to this program here. Let the robot send just a block of bytes. If you send continuously, the buffer gets overloaded and you can not see anymore what is coming in. It will be clear now, that there is no protocol.
I am happy to say that the code now works in the commercial as well as in the personal edition of Visual Prolog. The reason is that the personal edition now also has the package for multithreading, which is needed by this program.
Depending on what you want to do, you have the following choices
May be the following may help you a little.
RS232-ports are implemented as objects in this program.
In package serialports you find the needed predicates. First use serialport.cl to find the available ports with getSerialPortNames()/1 and then construct one with new()/1.
In the package Testing there is a class UserInterfaceRS232 which demonstrates how you can use the interface_predicates in serial.i.
In UserInterfaceRS232.pro comdevice contains the objectpointer for the RS232 port.If you search for comdevice in UserInterfaceRS232.pro you will quickly find a lot of examples.
Important are of course the predicates for clearing buffers, reading from and writing to a buffer, setting the parameters for baudrate, stopbits, parity and databits.
Package Examples is about using events. Waiting for an incomming character is demonstrated twice.
I sometimes use an evaluationversion of "Docklight". It can momentarily be found at Docklight. Another program I used was Tera Term. Both programs do not show the RS232-buffer, but you can at least see what they are sending.
Besides that I tested on a small microcontrollerboard build by a friend to send and receive data. In fact this last project was the reason for developping this packages. Later on I used an Atmel STK500 developmentboard without difficulties.
last version 03-10-2014 15.25