private ROVMessage ReceiveHelper()
{
ROVMessage msg = new ROVMessage();
while (ReadByte() != 0x42)
{
; //read in until header byte reached
}
msg.command = (byte)ReadByte();
msg.data = new byte[ReadByte()];
byte calculatedChecksum = (byte)msg.data.Length; //start calculating a checksum
for (int i = 0; i < msg.data.Length; i++)
{
//read in bytes one by one, calculating checksum as we go
msg.data[i] = (byte)ReadByte();
calculatedChecksum ^= msg.data[i];
}
byte actualChecksum = (byte)ReadByte();
if (calculatedChecksum != actualChecksum) //see if received checksum matches calculated one
{
throw new Exception(string.Format("Received corrupted data (Calculated checksum" +
" of {0} did not match received {1})", calculatedChecksum, actualChecksum));
}
return(msg);
}
//custom code for rov serial comms
public void TransmitRequestOrCommand(ROVMessage msg)
{
//assemble header, command, length bytes at front of message
byte[] temp = new byte[msg.data.Length + 4];
temp[0] = (byte)0x42;
temp[1] = msg.command;
temp[2] = (byte)msg.data.Length;
//checksum starts as msg length
byte calculatedChecksum = (byte)msg.data.Length;
//add all message data in
for (int i = 0; i < msg.data.Length; i++)
{
temp[i + 3] = msg.data[i];
calculatedChecksum ^= msg.data[i];
}
//add checksum
temp[temp.Length - 1] = calculatedChecksum;
//send it off
Write(temp, 0, temp.Length);
}
//handles communication and processing of queue
private void BackgroundLoop()
{
long prevTime = DateTime.Now.Ticks;
int thousandCount = 0;
int fiftyCount = 0;
while (!shuttingDown)
{
if (linkActive)
{
try
{
//update all queued devices
while (devices.Count > 0)
{
//send the request or command
devices.TryDequeue(out GenericAbstractDevice device);
port.TransmitRequestOrCommand(device.GetMessage());
//if it's a sensor and needs a reply
if (device.NeedsResponse)
{
//get the reply
ROVMessage msg = port.WaitReceiveData(1000);
//update the device's data on UI thread
device.Invoke(new Action(() => device.UpdateData(msg)));
}
//redraw the device on UI thread
device.Invoke(new Action(device.UpdateControls));
}
}
catch (Exception ex)
{
if (ex.GetType().IsAssignableFrom(typeof(System.Threading.ThreadAbortException)))
{
//log history before exception for debugging
Logger.LogString("Start Communication Log Dump\n" + port.GetHistory() + "\nEnd Communication Log Dump");
Logger.LogException(ex);
//cease communication
LinkActive = false;
//show exception dialog
if (CommunicationException != null)
{
CommunicationException(this, ex);
}
}
}
//fire timers if necessary
if ((DateTime.Now.Ticks - prevTime) > 10 * TimeSpan.TicksPerMillisecond)
{
//System.Diagnostics.Debug.WriteLine(DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond);
//System.Diagnostics.Debug.WriteLine(devices.Count);
prevTime = DateTime.Now.Ticks;
thousandCount++;
fiftyCount++;
if (thousandCount > 100)
{
thousandCount = 0;
if (ThousandElapsed != null)
{
ThousandElapsed(this, null);
}
}
else if (fiftyCount > 5)
{
fiftyCount = 0;
if (FiftyElapsed != null)
{
FiftyElapsed(this, null);
}
}
else
{
if (TenElapsed != null)
{
TenElapsed(this, null);
}
}
}
}
else
{
Thread.Sleep(100);
}
}
}
