Serial Terminal:

Controlling RealTerm from Matlab

Realterm now has an Examples directory, which contains more up-to-date examples than below RealtermDemo.m is on Download page

A Simple Demo

(What follows is for V5.3. V6.5 of matlab has changed some activeX stuff. eg enumerations now return strings, not numbers. See "Introducing New ActiveX Features in Matlab 6.5" )

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hrealterm=actxserver('realterm.realtermintf'); % start Realterm as a server
% Only use these 3 lines to see what properties and methods realterm has.....
fprintf(1,'\nProperties of Realterm\n\n');
get(hrealterm) %List all properties.
try
set(hrealterm) %In later versions of matlab, this will show you what possible values the enumerations can take
catch
end
fprintf(1,'\n\nMethods of Realterm\n\n');
invoke(hrealterm) %List all functions
% some example properties
hrealterm.baud=57600;
hrealterm.caption='Matlab Realterm Server';
hrealterm.windowstate=1; %minimized
hrealterm.PortOpen=1; %open the comm port
is_open=(hrealterm.PortOpen~=0); %check that it opened OK
hrealterm.displayas=2; %show hex in terminal window
hrealterm.CaptureFile='c:\temp\matlab_data.dat'
invoke(hrealterm,'startcapture'); %start capture
%do what you want here
fprintf(1,'\n\nTry what you want here. Type RETURN to end demo and close realterm\n')
keyboard
invoke(hrealterm,'stopcapture');
try %try to close any we can in case they are faulty.
invoke(hrealterm,'close'); delete(hrealterm);
catch
fprintf('unable to close realterm')
end; %try

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Using Capture

When you want to get data from an instrument, and process it in Matlab, I find it is easier to just capture data to a file with Realterm, then have Matlab read the file. This is a "design pattern" that appears ugly, but has been easy to get going, and sucessful. It is well decoupled, which is what makes it so easy to do.

The key point is that you can open a file for READ with Scilab, while Realterm has it open for WRITE

• Doesn't care how fast or slow matlab runs your program.
• serial comms runs in its own thread, completely independent of matlab
• very easy to get going and debug, as the matlab program just reads data into a file
• Matlab program can be tested on data files without real, working hardware

How:

• Start file capture. (Realterm opens file for write)
• Send commands to your instrument through Realterm using Putstring and Putchar. (see note about 0) or Sendfile
• Open file for read in matlab.
• Check Charcount in realterm. When there is some more data, read the file.
• Matlab can close and open the file for read, as much as it likes. However fileopen does take a little bit of time (ie 10's per second is OK, millions isn't)
• Seek to the last position in the file you read, and start reading from there. Seeking takes no time, even for files which are 10MB long.
• You might want to close the file every now and then if it gets to be many MB in length.
• Capturelength can set either how long Realterm captures for, or how many bytes it will capture

Using Sendfile

It can be even easier to just put outgoing commands into a file, and use SendFile to send them. By setting SendRepeats and SendDelay, you can make the commands repeat automatically, and just use your matlab program to read the data at its leisure. This technique is ideal for data logging applications.

Using Commandline:

If you don't want to use the ActiveX interface, then later versions of Realterm let you directly send commands repeatedly using sendfile, and sendrep, and using capture to get the result. You can use this with Scilab for example, as it doesn't have an activeX interface.

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