Communicating with a device

Hello everybody!

I am completely new to this problem. I have a digital weighing scale(a load cell hooked to a digital monitor) and I would like for MatLab to recognize it and communicate. Load cell is connected to the digital monitor and the monitor to my laptop. The connection is RS232, but I have a converter to USB, since my laptop does not support RS232.

So if someone could just stir me in the right direction, because I have no idea where to begin.

I'm guessing Instrument Control Toolbox? I have all the necessary info on the scale and it's outputs.

Anyone?

Answer 1

[Walter Roberson]

Please see my Answer to this question to see the general procedures for working with serial ports. That particular question is focused on communication with a robot, but the outline I gave there applies to your case.

You will not need the Instrument Control Toolbox.

You will need to have your digital scale connected up before your start your MATLAB session, and you will need to take in to account that the device name of a USB device is not constant. See instrfind() to retrieve the list of serial devices.

[Slobodan Djordjevi?]

Walter thank you for this!

But I still have several questions...

I don't think my code below recognizes the scale. The scale is connected via (RS232 - USB) to COM6(looked up in Device manager).

The scale monitor now is showing 0.00kg. How do I get this information to .txt file.

The Code :

clc;

clear all;

s1 = serial('COM6'); % define serial port

s1.BaudRate=9600; % define baud rate

set(s1, 'terminator', 'LF'); % define the terminator for println

fopen(s1);

data = fgetl(s1, '%s');

fid = fopen('tehtnica.txt', 'wt');

fprintf(fid, '%s', data);

fclose(fid);

fclose(s1);

Help me on this one, please!

[Walter Roberson]

fgetl() does not accept a format: it always returns a string.

You might want to change your output format to

fprintf(fid, '%s\n', data);

I do not know how your scale operates; it would be common for you to need to send a command to the scale to provoke it to send the current reading back.