Automatic Timeout with Serial Ports

Unity Engine
1

As part of a side project, I am trying to get input from a serial port, but am having a bit of trouble getting Unity to even run properly.

While using the code below, I get this error on the first frame.

TimeoutException: The operation has timed-out.
System.IO.Ports.WinSerialStream.Read (System.Byte[] buffer, Int32 offset, Int32 count)
System.IO.Ports.SerialPort.read_byte ()
System.IO.Ports.SerialPort.ReadByte ()
(wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:ReadByte ()
ArduinoInput.Update () (at Assets/ArduinoInput.cs:25)

using UnityEngine;
using System.IO.Ports;

public class ArduinoInput : MonoBehaviour {

    public float speed;
    private float amountToMove;

    SerialPort sp = new SerialPort("COM4", 9600);

    void Start ()
    {
        sp.Open();
        sp.ReadTimeout = 1;
    }
  
    void Update ()
    {
        amountToMove = speed * Time.deltaTime;

        if (sp.IsOpen)
        {
            try
            {
                MoveObject(sp.ReadByte());
                print(sp.ReadByte());
            }

            catch (System.Exception)
            {
                throw;
            }
        }
    }

    void MoveObject(int direction)
    {
        if (direction == 1)
        {
            transform.Translate(Vector3.left * amountToMove, Space.World);
        }

        if (direction == 2)
        {
            transform.Translate(Vector3.right * amountToMove, Space.World);
        }
    }
}
2

Update:

I have debugged the exception and have gathered the following information from it.

System.TimeoutException: The operation has timed-out.
  at System.IO.Ports.WinSerialStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  at System.IO.Ports.SerialPort.read_byte () [0x00000] in <filename unknown>:0
  at System.IO.Ports.SerialPort.ReadByte () [0x00000] in <filename unknown>:0
  at (wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:ReadByte ()
  at ArduinoInput.Update () [0x00022] in D:\Labyrith\Tabletop\Assets\ArduinoInput.cs:26
UnityEngine.MonoBehaviour:print(Object)
ArduinoInput:Update() (at Assets/ArduinoInput.cs:34)
3

Hi, I’m getting the exact same error as you. Did you ever manage to get round this problem?

4

Currenty,I met a simalar problem like this,hope to get an answer

5

Your timeout is set to 1 millisecond which will most likely timeout instantly. Raise it to a more sane number like 500ms or 1000ms.

6

Did anyone ever find a solution to this? Neither changing the delay() value in Arduino no the serial port timeout in Unity helps.

7

I had the same problem, I put Serial.flush(); on the arduino code in setup function and boom, the problem solved…

8

Setting my timeOut to 5000 milliseconds fixed it. Im also threading the signal from the arduino. Used this article here:
https://www.aryanbhasin.com/blog/reduce-delays-in-serial-port-communication-in-unity

9

I had a similar problem where attempting to read from SerialPort in Unity would cause a timeout regardless of what my readTimeout was set to.

Setting DtrEnable = true on my SerialPort object seems to fix it for me.

1 Like
10

Thanks for your help Ortega-Dev. None of the above doesnt work. but yours fixed it thanks.

1 Like
11

For ppl still looking for an answer to this what I di is before I write any data I set my new line

portname.SetNewLine = "\n"
portname.Write("something" + "\n")
12

Setting DtrEnable = true on my SerialPort object seems to fix it for me as well. Thanks!