fopen does not work for filename given by fullfile

Hi

I tried to read input data from a file as follows. However it returns an error such that; "Error using fopen First input must be a file name of type char, or a file identifier of type double."

 main_data_path ='/usr/local/MATLAB/......';
folder = fullfile(main_data_path, 'row_data',...
                                        {'data1.dat';...
                                           'data2.dat';...
                                           'data3.dat';...
                                           'data3.dat';});
disp(folder);
data1 =  folder(1,1);
fileID = fopen(data1);

Can anyone please let me know what is wrong in this code?

Thanks you so much in advance! Best,

Answer 1

[KSSV]

Try

fileID = fopen(data1{1})

Instead of

fileID = fopen(data1);

fopen needs a filepath as a character, your data1 is a cell.

[Hyon Kim]

ah, I see. This works. Thanks a lot!

Answer 2

[Kevin Daniel Resendiz Rivera]

hi, i have a this problem

s = serialport("COM3",9600); % Abre el puerto serie

fopen(s); % Abre la conexión

figure; % Crea la figura

plot(0,0); % Crea la línea inicial

while ishandle(1) % Bucle hasta que se cierre la figura

data = fscanf(s,"%f"); % Lee la temperatura del puerto serie

x = get(gca,"XLim").*[1 1]; % Obtiene los límites actuales del eje X

y = [get(gca,"YLim");data data]; % Añade la temperatura a los datos

set(1,"XData",x,"YData",y); % Actualiza la figura

drawnow; % Redibuja la figura

end

fclose(s); % Cierra la conexión

Error using fopen

First input must be a file name or a file identifier.

Error in mezfinal (line 2)

fopen(s); % Abre la conexión

[Steven Lord]

There's no fopen object function listed on the serialport object's documentation page. Creating the object should open the port without need to call fopen or open or the like.

Is there something on a documentation page that led you to believe you needed to open the object before using it?

[Kevin Daniel Resendiz Rivera]

Hello, thank you for answering

So I delete the fopen or what would be the solution?

What I'm trying to do is send data from a sensor from the Arduino for matlab to graify it

This is the arduino code: #include SPI.h #include max6675.h

const int thermoDO = 12; const int thermoCS = 11; const int thermoCLK = 13;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

void setup() { Serial.begin(9600); // Inicia el puerto serie }

void loop() { double celsius = thermocouple.readCelsius(); // Lee la temperatura del MAX6675 Serial.println(celsius); // Envía la temperatura al ordenador delay(1000); // Espera un segundo }

And the one above is all the matlab code.

I would like you to help me since I'm new to matlab, thank you