Writing to serial ports. (arduino)

I am attempting to do some force feedback with an arduino and decided to start simply by sending things to it via serial. That on its own gave me problems.

My script:

using UnityEngine;
using System.Collections;
using System.IO.Ports;

public class NewBehaviourScript : MonoBehaviour {

SerialPort sp = new SerialPort("COM4", 9600);
// Use this for initialization
void Start () {
sp.Open();
}

// Update is called once per frame
void Update () {

sp.Write("25");


}
}

gave me this error:

InvalidOperationException: Specified port is not open.
System.IO.Ports.SerialPort.CheckOpen ()
System.IO.Ports.SerialPort.Write (System.String str)
(wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:Write (string)
NewBehaviourScript.Update () (at Assets/Scripts/NewBehaviourScript.cs:16)

tl;dr its telling me that the port isn't open.

I am using the correct com port and I open the port in the script. I checked that the arduino is in fact on COM4. I have no idea what may be causing this, and I doubt it is something on the arduino side because reading serially from the arduino works perfectly fine when using the Arduino IDEs serial monitor.

To clear up one more thing: yes, i did change the player settings to use .NET 2.0 instead of .NET 2.0 subset.

I know my problem is me doing or missing something extremely stupid, but please bear with me.

 

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Maybe try sending from a function invokes in start with "InvokeRepeating"? Also are you sure that you don't need more to the new SerialPort? I worked with serial ports a while ago and had more than just the port name and baud rate?

this is a link to my work with serial ports in Unity (can't be built to webplayer) does that work? I know that works for serial stuff.

 

Hi ThaHypnotoad,
did you manage to solve the problem?

 

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