易语言deviceiocontrol
时间: 2023-08-10 11:02:50 浏览: 109
易语言的 DeviceIoControl 函数用于向设备发送控制码,可以用于读取或写入设备的数据。该函数的语法如下:
```
Declare Function DeviceIoControl Lib "kernel32.dll" Alias "DeviceIoControl" (ByVal hDevice As Long, ByVal dwIoControlCode As Long, lpInBuffer As Any, ByVal nInBufferSize As Long, lpOutBuffer As Any, ByVal nOutBufferSize As Long, lpBytesReturned As Long, lpOverlapped As Any) As Long
```
其中,参数说明如下:
- hDevice:设备句柄。
- dwIoControlCode:控制码。
- lpInBuffer:输入缓冲区。
- nInBufferSize:输入缓冲区大小。
- lpOutBuffer:输出缓冲区。
- nOutBufferSize:输出缓冲区大小。
- lpBytesReturned:实际传输的字节数。
- lpOverlapped:指向异步操作的 OVERLAPPED 结构体的指针。
使用该函数前需要先打开设备句柄,例如:
```
hDevice = CreateFile("\\.\COM1", GENERIC_READ Or GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0)
```
然后可以使用 DeviceIoControl 函数进行读写操作,例如:
```
Dim dwBytesReturned As Long
Dim dwControlCode As Long
Dim InBuffer As String * 256 '输入缓冲区
Dim OutBuffer As String * 256 '输出缓冲区
dwControlCode = 0x1234 '控制码
InBuffer = "Input data" '输入数据
DeviceIoControl hDevice, dwControlCode, InBuffer, Len(InBuffer), OutBuffer, Len(OutBuffer), dwBytesReturned, 0
If dwBytesReturned > 0 Then
'从输出缓冲区读取数据
End If
```
注意,使用 DeviceIoControl 函数需要具有管理员权限。