[Interest] Simple UDP listener question

[Robert Wood]

Folks,

I've managed to get a simple program going that sends out a UDP packet 
to a broadcast address (an Artnet Poll packet) and my embedded software 
is receiving this and sending out a Poll reply. Wireshark confirms that 
my embedded device is sending out the correct response, however, my Qt 
program is not picking up any reply at all. I should say, this is the 
first time I've used Qt for networking and it's my first embedded 
netowrking project, so I may be missing some very basic point.

I am doing this in MainWindow initialisation:

     udpSocSend = new QUdpSocket(this);
     udpSocRec = new QUdpSocket(this);
     udpSocSend->bind(QHostAddress("192.168.0.18"),6454);
     udpSocRec->bind(6454, QUdpSocket::ShareAddress);
     connect(udpSocRec, SIGNAL(readyRead()),this, 
SLOT(processPendingDatagrams()));

void MainWindow::processPendingDatagrams()
{

     while (udpSocRec->hasPendingDatagrams())
         {
         QByteArray datagram;
         datagram.resize(udpSocRec->pendingDatagramSize());
         udpSocRec->readDatagram(datagram.data(), datagram.size());
         ui->textEdit->setText(tr("Received datagram: 
\"%1\"").arg(datagram.data()));

         }
}

My udpSocSend is working to send data out (an Artnet Poll), my STM32 
(embedded micro) is sending packets back according to Wireshark, but 
processPendingDatagrams() flatly refuses to be called!

Wireshark shows this in terms of a reply:

2475	795.416268000	192.168.0.177	192.168.0.18	ARTNET	282	ArtPollReply 
(0x2100)

The STM32 is at address 192.168.0.177, my [Linux] Qt machine is 
192.168.0.18.

The data in the datagram looks OK mto me on Wireshark.

Can anyone see anything I am doing wrong please?

Thanks!

Rob