C#

private void timer1_Tick(object sender, System.EventArgs e)
{
//initialise connection to my hardware thru com1

ArrayList frames = this.gCont.GetResponseFrames();

foreach(byte[] frame in frames)
{
//do my stuffs
}
}

		
}

using System.Net;
using System.Runtime.InteropServices;

class Arp
{

    [DllImport("iphlpapi.dll", ExactSpelling = true)]
    private static extern int SendARP(int DestIP, int SrcIP, [Out] byte[] pMacAddr, ref int PhyAddrLen);

    public string MyMethodName()
    {
        string LocalHostName = Dns.GetHostName();
        string[] Ipaddr = new string[3];
        Ipaddr[0] = LocalHostName;
        System.Net.IPHostEntry LocalIpAddress = Dns.GetHostEntry(LocalHostName);
        System.Net.IPAddress[] FirstAddress = LocalIpAddress.AddressList;
        foreach (IPAddress TempA in FirstAddress)
        {
            Ipaddr[1] = TempA.ToString();
            byte[] ab = new byte[6];
            int len = ab.Length;
            int r = SendARP((int)TempA.Address, 0, ab, ref len);
            Ipaddr[2] = BitConverter.ToString(ab, 0, 6);
        }
    }
}

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using System;<br />
using System.Runtime.InteropServices;<br />
using System.Net;<br />
<br />
/// <summary><br />
/// ARP scanner version 0.1<br />
/// </summary><br />
public class Arp<br />
{<br />
    [DllImport("iphlpapi.dll", ExactSpelling = true)]<br />
    public static extern int SendARP(<br />
        int DestIP,<br />
        int SrcIP,<br />
        [Out] byte[] pMacAddr,<br />
        ref int PhyAddrLen);<br />
    public string CollectList()<br />
    {<br />
        for (int i = 20; i < 70; i++)<br />
        {<br />
            String sStatus;<br />
            String IPString = "192.168.0." + i;<br />
            string[] _splitString = IPString.Split(new char[] { '.' });<br />
<br />
            int _retVal = 0;<br />
            _retVal += (int)(int.Parse(_splitString[3]) * Math.Pow(256, 0));<br />
            _retVal += (int)(int.Parse(_splitString[2]) * Math.Pow(256, 1));<br />
            _retVal += (int)(int.Parse(_splitString[1]) * Math.Pow(256, 2));<br />
            _retVal += (int)(int.Parse(_splitString[0]) * Math.Pow(256, 3));<br />
            _retVal = (int)(((_retVal & 0x000000ff) << 24) +<br />
            ((_retVal & 0x0000ff00) << 8) +<br />
            ((_retVal & 0x00ff0000) >> 8) +<br />
            ((_retVal & 0xff000000) >> 24));<br />
<br />
            byte[] ab = new byte[6];<br />
            int len = ab.Length;<br />
            int r = SendARP((int)_retVal, 0, ab, ref len);<br />
            string sMac = BitConverter.ToString(ab, 0, 6);<br />
<br />
            if (sMac == "00-00-00-00-00-00")<br />
            {<br />
                sStatus = "<font color = red>Offline</font>";<br />
            }<br />
            else<br />
            {<br />
                sStatus = "<font color = green>Online</font>";<br />
            }<br />
<br />
            // Response.Write("<BR>IP addresse: 192.168.0." + i + " " + sStatus);<br />
            // Response.Write("<BR>" + _retVal);<br />
            // Response.Write("<BR>Mac addresse:" + sMac);<br />
        }<br />
    }<br />
}