.net – SerialPort – Clear Existing Data

I'm using the .NET SerialPort class to communicate with gauges. Every time a button on a gauge is pressed a reading value is sent over port.

The problem I have is that if the gauge button is pressed while the program is off then when the program starts it fires the data received event for that existing data. I don't want this behavior — I only want to collect readings done after the port is opened.

I have a current workaround using a Thread.Sleep but it seems hacky and I'm wondering if anyone knows of a better solution.

port = New SerialPort("COM1", 9600, Parity.None, 8, StopBits.One)

port.Open()
port.DtrEnable = True

System.Threading.Thread.Sleep(100)
port.ReadExisting()

AddHandler port.DataReceived, AddressOf PortDataReceived

If I don't have the Thread.Sleep then the DataReceived event is fired for the previous gauge data. I'm guessing this is because the ReadExisting doesn't block and so when its called immediately after an open it just reads nothing.

Thanks

So if you call 'port.BytesToRead()' immediately after open its zero. If you call it 100ms after open its non-zero. I guess this makes sense — it takes time after open to read the existing data.

Another option is to call read and set the read timeout but that seems no different than Thread.Sleep except you have to catch an exception…