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Author Topic: (SOLVED) Arduino + Mono + Reading from serial (the operation has timed out)  (Read 2365 times)
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My Development Environment:

- Hardware: Arduino MEGA 2560/UNO (firmwares: arduino-usbserial-mega.hex/arduino-usbserial-uno.hex)
- Hardware: MACBOOK PRO 13i 2011
- Software:  MAC OSX 10.6.7
- Software:  Arduino 0022
- Software:  Monodevelop 2.4.2

Problem sample code: http://arduino.cc/playground/Interfacing/Mono

// SerialTest.cs
//
// The MIT License
//
// Copyright (c) 2008 Matias Korhonen
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
using System;
using System.IO.Ports;

class MainClass
{  
   public static void Main(string[] args)
   {
      SerialPort sport = new SerialPort("/dev/tty.usbmodemfa131", 9600);

      if (sport != null)
      {
         if (sport.IsOpen)
            {
               sport.Close();
            }
      }

      Console.WriteLine("Arduino Serial Test");

      sport.Open();

      while(true)
      {      
         Console.WriteLine(sport.ReadLine());
      }
   }

}

Results in this output:

Unhandled Exception: System.TimeoutException: The operation has timed-out.
  at System.IO.Ports.SerialPortStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00086] in /private/tmp/monobuild/build/BUILD/mono-2.6.7/mcs/class/System/System.IO.Ports/SerialPortStream.cs:151
  at System.IO.Ports.SerialPort.read_byte () [0x00007] in /private/tmp/monobuild/build/BUILD/mono-2.6.7/mcs/class/System/System.IO.Ports/SerialPort.cs:608
  at System.IO.Ports.SerialPort.ReadTo (System.String value) [0x00042] in /private/tmp/monobuild/build/BUILD/mono-2.6.7/mcs/class/System/System.IO.Ports/SerialPort.cs:670
  at System.IO.Ports.SerialPort.ReadLine () [0x00000] in /private/tmp/monobuild/build/BUILD/mono-2.6.7/mcs/class/System/System.IO.Ports/SerialPort.cs:653
  at (wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:ReadLine ()
  at ArduinoSerial001.MainClass.iThread_Daemon_Start () [0x00020] in /Users/bartjanssen/Projects/Monodevelop/Arduino-Serial-001/Arduino-Serial-001/Main.cs:68
The application was terminated by a signal: SIGHUP

Question:

What could be wrong and be the reason for the time out ?
« Last Edit: April 02, 2011, 04:48:26 pm by Snotter » Logged

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Quote
What could be wrong and be the reason for the time out ?
Read the data coming in on the serial port, or generate a time out exception if no data arrives within a reasonable time. Hmm, now why would a time out exception be being generated.

Code:
      SerialPort sport = new SerialPort("/dev/tty.usbmodemfa131", 9600);
This doesn't look like any port name I'm familiar with.
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FYI:

/dev/tty.usbmodemfa131 is the device name on MAC OSX , in linux it's ttyACM0/1/... , in windows it's COM3/4/...
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... adding a timeout exception results in an endless loop of time-out after time-out.

The only way i'm able to read from the serial device is by using "screen /dev/tty.usbmodemfa131" in a terminal ...

What could "screen" be doing different in handling the serial communication connection ... ?
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SOLUTION FOUND:

Apparantly when you connect an Arduino UNO/MEGA to a MAC system you get two devices loaded, in my case /dev/tty.usbmodemfd121 and /dev/cu.usbmodemfd121 ...

All the time and effort I put in above was tested with /dev/tty.usbmodemfd121 and with no luck ...
(I use /dev/tty.usbmodemfd121 as a reference in the Arduino IDE 0022 to upload and read from the serial)

Changing to /dev/cu.usbmodemfd121 in the code DOES WORK  and makes reading from the serial possible !!!

I couldn't find anything about this in the manuals , it might be worth adding imo.

Woot!
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