/// <summary>
/// Handler for timers Elapsed event
/// </summary>
/// <param name="sender">Timer instance that triggered event</param>
/// <param name="e">Arguments</param>
private void TimeoutHandler(object sender, System.Timers.ElapsedEventArgs e)
{
if (Connected)
{
if (ActualState == ModbusAsciiLinkState.IDLE)
{
// Timeout occured but bus is idle (message processed) should not happen
TimeoutCounter.Stop();
Debug.WriteLine("LINK - IDLE_TIMEOUT");
return;
}
if (ActualMessageId != TkickMessageId)
{
// Timeout occured but link is already handling another message - should not happen
TimeoutCounter.Stop();
Debug.WriteLine("LINK - BUSY_TIMEOUT");
return;
}
// Timeout occured and link is stuck, reset (required transport layer for handling possible data loss)
Debug.WriteLine("LINK - STUCK_TIMEOUT");
ActualFrameIndex = 0;
ActualMessageId = 0;
TkickMessageId = 0;
TriggerTimeoutOccured();
ActualState = ModbusAsciiLinkState.IDLE;
return;
}
}
/// <summary>
/// Close bus connection
/// </summary>
/// <returns>true if success, false if error</returns>
public bool Disconnect()
{
// Stop link thread
LinkThread.Abort();
ActualState = ModbusAsciiLinkState.IDLE;
return(PHY.Disconnect());
}
/// <summary>
/// Open connection and access bus
/// </summary>
/// <returns>true if success, false if error</returns>
public bool Connect()
{
if (PHY.Connect())
{
// Start the link thread if connection was successful
ActualState = ModbusAsciiLinkState.IDLE;
LinkThread.Start();
return(true);
}
return(false);
}
/// <summary>
/// Task for processing received data running in thread
/// </summary>
private void ModbusAsciiLinkTask()
{
int threadDelay = 10;
while (true)
{
Thread.Sleep(threadDelay);
// Pop byte from receive ring buffer
int value = PHY.Receive();
if (value != -1)
{
byte ReceivedByte = Convert.ToByte(value);
switch (ActualState)
{
// Link is idle, wait for start character
case ModbusAsciiLinkState.IDLE:
if (ReceivedByte == ':')
{
// Start character received, start timeout timer and set state to receiving
TkickMessageId = ActualMessageId;
TimeoutCounter.Start();
// Reset reception buffer index
ActualFrameIndex = 0;
threadDelay = 0;
ActualState = ModbusAsciiLinkState.RECEIVING;
}
break;
case ModbusAsciiLinkState.RECEIVING:
// Link is receiving a message
if (ReceivedByte == '\n')
{
// Stop character received, stop timeout timer
TimeoutCounter.Stop();
// Check data integrity and notify upper layer
ProcessReceivedData();
// Set state to idle
ActualState = ModbusAsciiLinkState.IDLE;
threadDelay = 10;
// Increment message id
ActualMessageId++;
break;
}
if (ReceivedByte == '\r')
{
// do not store CR character
break;
}
if (ActualFrameIndex < ActualFrame.Length)
{
// Write received byte buffer
ActualFrame[ActualFrameIndex++] = ReceivedByte;
}
// If buffer overflow occured, skip and wait for timeout
break;
default:
break;
}
}
}
}
