[Linux] /dev/ttySAC0 - how can I read that file?

[Tomasz]

Hello!

I want to read (only read) /dev/ttySAC0. I wrote simple program in C, and It works fine in console. Now I want to do the same using QT. But when I want to read from that file program hangs. Any ideas what can I do? Data in that file is refreshing in every 1 second and it comes by RS232 from another device.

thanks in advance
best regards
Tomasz

[tbscope]

What have you tried so far?
You mention that your program hangs.

[Tomasz]

I've tried something like this:



QFile file("/dev/ttySAC2");

int len = 0;
char buffer[100];


if (!file.open(QIODevice::ReadOnly)) {
printf("error!");
} else {
int pending = file.bytesAvailable();
out << QString::number(pending) << endl;

if ( pending > 0 ) {
len = file.read(buffer, sizeof buffer - 1);
}

if (len > 0) {
[...]
}


And also something with QTextStream. Program hangs when it is trying to read from that file. In console program there was no problem.

thanks in advance
best regards
Tomasz

[kuzulis]

Tomasz,

try use library for serial programming in Qt4:
1. QSerialDevice (in gitorgious.org)
2. qextserialport (in google.com)
3. qserialport (in gitorgious.org)

and etc. analogs.

Choose yourself what you like.

[Tomasz]

But maybe someone have any idea how can i read from that file using standard classes?

thanks in advance
best regards
Tomasz

[wysota]

Use QLocalSocket and optionally QSocketNotifier.

[Tomasz]

Use QLocalSocket and optionally QSocketNotifier.

How can I use QLocalSocket with file?

thanks in advance
best regards
Tomasz

[squidge]

How about:



int fd = open("/dev/ttySAC0", O_RDONLY|O_NONBLOCK);
QSocketNotifier *socNotify = new QSocketNotifier(fd, QSocketNotifier::Read, this);
connect(socNotify, SIGNAL(activated(int)), this, SLOT(your_read_function(int)));

[wysota]

How can I use QLocalSocket with file?
/dev/ttySAC0 is not a file, it's a stream you can connect to using QLocalSocket. Or you can use QSocketNotifier with native stream handling (see the example squidge gave you).