You could switch to using a AutoResetEvent
wait handle:
public void sendUsbData(byte _txData)
{
byte[] txData = new byte[this.usb.SpecifiedDevice.OutputReportLength];
txData[1] = 0x50; // 0x50 = loopback command. Element 0 is always 0x00
int pos = 2;
foreach (byte b in _flashData)
{
txData[pos] = b;
pos++;
}
// reset member wait handle
waitHandle = new AutoResetEvent(false);
this.usb.SpecifiedDevice.SendData(txData);
}
private void usb_OnDataRecieved(object sender, DataRecievedEventArgs args)
{
this.ParseReceivePacket(args.data); // Format to string and print to textbox
// signal member wait handle
waitHandle.Set();
}
And then in your for loop:
for (int i = 0; i > 16; i++)
{
sendUsbData(array[i]);
// wait for member wait handle to be set
waitHandle.WaitOne();
}