获取远程设备内所有通道的连接状态，注意需要先登录设备，详细请参考上一节设备登录

通道连接状态说明

public enum EM_CAMERA_STATE_TYPE
{
    UNKNOWN,	//未知
    CONNECTING,	//正在连接
    CONNECTED,	//已连接（在线）
    UNCONNECT,	//未连接（掉线）
    EMPTY,		//通道未配置,无信息
    DISABLE		//通道有配置,但被禁用
}

获取通道状态方法

public static NET_CAMERA_STATE_INFO[] GetDeviceStatus()
{
    if (m_loginID == IntPtr.Zero) return null;
    IntPtr intPtr = IntPtr.Zero;
    IntPtr outPtr = IntPtr.Zero;
    NET_IN_GET_CAMERA_STATEINFO inParam = new NET_IN_GET_CAMERA_STATEINFO();
    NET_OUT_GET_CAMERA_STATEINFO outParam = new NET_OUT_GET_CAMERA_STATEINFO();

    inParam.dwSize = (uint)Marshal.SizeOf(typeof(NET_IN_GET_CAMERA_STATEINFO));
    inParam.bGetAllFlag = true;
    outParam.dwSize = (uint)Marshal.SizeOf(typeof(NET_OUT_GET_CAMERA_STATEINFO));
    outParam.nMaxNum = m_DeviceInfo.nChanNum;
    outParam.pCameraStateInfo = Marshal.AllocHGlobal(outParam.nMaxNum * Marshal.SizeOf(typeof(NET_CAMERA_STATE_INFO)));

    intPtr = Marshal.AllocHGlobal((int)inParam.dwSize);
    Marshal.StructureToPtr(inParam, intPtr, true);
    outPtr = Marshal.AllocHGlobal((int)outParam.dwSize);
    Marshal.StructureToPtr(outParam, outPtr, true);
    //获取设备连接状态
    bool res = NETClient.QueryDevInfo(m_loginID, EM_QUERY_DEV_INFO.GET_CAMERA_STATE, intPtr, outPtr, 3000);
    if (!res)
    {
        return null;
    }
    outParam = (NET_OUT_GET_CAMERA_STATEINFO)Marshal.PtrToStructure(outPtr, typeof(NET_OUT_GET_CAMERA_STATEINFO));

    if (outParam.nValidNum > 0)
    {
        var status = new NET_CAMERA_STATE_INFO[outParam.nValidNum];
        for (int i = 0; i < outParam.nValidNum; i++)
        {
            status[i] = (NET_CAMERA_STATE_INFO)Marshal.PtrToStructure(outParam.pCameraStateInfo + i * Marshal.SizeOf(typeof(NET_CAMERA_STATE_INFO)), typeof(NET_CAMERA_STATE_INFO));
        }
        return status;
    }
    return null;
}