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jcurl / RJCP.DLL.SerialPortStream

SerialPortStream is an independent implementation of System.IO.Ports.SerialPort and SerialStream for better reliability and maintainability. Default branch is 2.x and now has support for Mono with help of a C library.
Microsoft Public License
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Long delay when opening a serial port (around 30 seconds) #12

Closed tbayne closed 7 years ago

tbayne commented 7 years ago

I am seeing a long delay when doing a .Open() on a serial port stream. Delays of 15 to 30+ seconds are common.

A run of the VS 2015 performance profile shows that the delay appears to be in:

Ports.Native.Windows.CommModemStatus.ClearCommBreak().

Is this expected?
Note that this a USB virtual COM port.

jcurl commented 7 years ago

Hello Terry,

I've not observed this behavior myself. Can you describe a little more of your setup? What driver are you using and what is the actual hardware? Have tried different drivers, like FTDI or Prolific?

I expected the method to just internally clear flags and not be more than the order of milliseconds. Do you use hardware flow control at all?

Sent from my Windows Phone

From: Terry Baynemailto:notifications@github.com Sent: ‎27/‎12/‎2016 15:04 To: jcurl/SerialPortStreammailto:SerialPortStream@noreply.github.com Cc: Subscribedmailto:subscribed@noreply.github.com Subject: [jcurl/SerialPortStream] Long delay when opening a serial port (around 30 seconds) (#12)

I am seeing a long delay when doing a .Open() on a serial port stream. Delays of 15 to 30+ seconds are common.

A run of the VS 2015 performance profile shows that the delay appears to be in:

Ports.Native.Windows.CommModemStatus.ClearCommBreak().

Is this expected? Note that this a USB virtual COM port.

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHubhttps://github.com/jcurl/SerialPortStream/issues/12, or mute the threadhttps://github.com/notifications/unsubscribe-auth/ABfbf3ZxNbGc27exd0xOfTygjO902qj9ks5rMRrJgaJpZM4LWSrA.

tbayne commented 7 years ago

Jason,

Thank you for the quick response.

The device I am using is a "FlexControl" from FlexRadio Systems. It came with a a VSP driver, which is what I am using. (Running at 9600, 8,None,1) on COM99. No flow control is turned on. Note that once the port is opened it works perfectly.

This is something I can live with (and potential users of my utility aren't likely going to want to change drivers). I just wanted to check that this wasn't expected behavior.

I will put this on the back burner for now and may try to get the device working with alternate drivers in the future. Once I do, I will report back my findings.

Happy New Year Terry

jcurl commented 7 years ago

Hello, I'm attaching a test binary. I've removed the code that calls this method on open and would like your confirmation that it works for you as expected.

SerialPortStream-2.0.3-Debug-0a840dc.zip

tbayne commented 7 years ago

Jason,

I will try this out this afternoon and report back.

Terry

On Thu, Dec 29, 2016 at 7:15 AM, Jason Curl notifications@github.com wrote:

Hello, I'm attaching a test binary. I've removed the code that calls this method on open and would like your confirmation that it works for you as expected.

SerialPortStream-2.0.3-Debug-0a840dc.zip https://github.com/jcurl/SerialPortStream/files/677131/SerialPortStream-2.0.3-Debug-0a840dc.zip

— You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub https://github.com/jcurl/SerialPortStream/issues/12#issuecomment-269628799, or mute the thread https://github.com/notifications/unsubscribe-auth/ABiY_ZcR-TsofYcNlpIK61yvybEV28SCks5rM7KPgaJpZM4LWSrA .

tbayne commented 7 years ago

Jason,

I managed to fit this in this morning. I can report that it works much better - the Open() call now takes on the order of 19ms rather than 30000ms - much improved.

I call this a win!

Terry