Help using QSerialPort

silviutp

I am having trouble sending commands to a motor through a serial interface.
Bellow I try to send a homing command (first byte is the device id, second byte is the command, and there are 4 more bytes of data which are not used for this command)
@int main(){
QSerialPortInfo info("COM1");
qDebug()<<info.manufacturer()<<endl;
qDebug()<<info.description()<<endl;
qDebug()<<info.portName()<<endl;
QSerialPort port(info);

port.setBaudRate(QSerialPort::Baud9600);
port.setDataBits(QSerialPort::Data8);
port.setFlowControl(QSerialPort::NoFlowControl);
port.setParity(QSerialPort::NoParity);
port.setStopBits(QSerialPort::OneStop);
port.open(QSerialPort::ReadWrite);

char cmd_data[]={0,1,0,0,0,0};
port.write(cmd_data);
delay(3000); // delay 3s

cout<<"Closing Serial Port"<<endl;
port.close();
return 0;

}@
Nothing happens.... The device works with an external program..
What am I doing wrong ? Is this the right way to send the command ?

kqt-mr-nv6

first you have to open the port
and then do the settings

and also
consider the return status of all the settings and
port open methods

qxoz

Hi.
Did you check is serialport opened and data realy sended? If yes try compare real data sended to a device from your programm and external programm. Are they identical?
You can use "free serialport monitor":http://www.serial-port-monitor.com/ for that.

kuzulis

Hi.

Yes, please do all as guys says...

Also this wrong:

[code]
...
port.write(cmd_data);
delay(3000); // delay 3s
...
[/code]

need:
[code]
...
port.write(cmd_data);
waitForBytesWritten(3000); // delay 3s
...
[/code]

silviutp

[quote author="kqt-mr-nv6" date="1383819968"]first you have to open the port
and then do the settings
[/quote]
thank you, that was the problem

silviutp

Hi
I am having a problem communicating with my motor. When I give it some commands that take more time to realize (for example a long move or a home command) I am having problem when reading a response in the sense that I cannot always get the 6 bytes corresponding to a response. This thing also happens when I use a Sleep function (from "windows.h") with sufficient time for the command to complete.
I have this functions for sending...
@bool MotorAccess::sendCommand(const QByteArray& cmd){
int bytes_sent = port_->write(cmd);
if (bytes_sent != 6){
return false;
}
port_->waitForBytesWritten(100);

return true;
}@
and reading...
@QByteArray MotorAccess::getResponse(){
bool read_success = true;
QByteArray response = QByteArray();// = port_->readAll();

// discard data if buffers have more data then needed
// this can happen when manual accessing the motor
while (port_->bytesAvailable()>6) {
#ifdef DEBUG_MODE
qDebug()<<port_->bytesAvailable();
#endif
port_->read(1);
}

read_success = port_->waitForReadyRead(100);
if (port_->bytesAvailable() == 0) {
return response;
}
response.append(port_->read(1));

while (read_success && response.count() < 6 ){
read_success = port_->waitForReadyRead(100);
response.append(port_->read(1));
}
if ((! read_success) || response.count() != 6) {
#ifdef DEBUG_MODE

   qDebug()<<"Read Problem. Bytes available: "<<port_->bytesAvailable();

#endif
}

return response;
}@
I would really appreciate some help on this. Thanks