DioNotifyTrg

Function

Starts monitoring the trigger of the specified logical bit.

Format

Ret = DioNotifyTrg ( Id , TrgBit , TrgKind , Tim , hWnd )

Parameters

Id [ VB.NET: Short ] [ C, C++: short ] [ C#: short ] [ Python: ctypes.c_short ]
Specify the device ID retrieved from DioInit.

TrgBit [ VB.NET: Short ] [ C, C++: short ] [ C#: short ] [ Python: ctypes.c_short ]
Specify the logical input bit which is monitored the trigger. The maximum number of bits for monitoring the trigger is 255.

TrgKind [ VB.NET: Short ] [ C, C++: short ] [ C#: short ] [ Python: ctypes.c_short ]
Specify the rising edge, falling edge or logical sum of both sides for the monitoring content of a specified bit. The following definition values are valid.

Tim [ VB.NET: Integer ] [ C, C++: long ] [ C#: int ] [ Python: ctypes.c_long ]
Specify the period of trigger monitor in the unit of "msec". The period of trigger monitor is set for each device separately.
The settable range for DI-XX(USB) and DIO-XX/XX(USB) is 1 msec to 2147483647 msec.
For other devices is 10 msec to 2147483647 msec.

hWnd [ VB.NET: IntPtr ] [ C, C++: HWND ] [ C#: IntPtr ] [ Python: ctypes.wintypes.HANDLE ]
Specifies the window handle to receive the trigger message.
The window handle can be retrieved by m_hWnd in VC.

Return Value

Ret [ VB.NET: Integer ] [ C, C++: long ] [ C#: int ] [ Python: ctypes.c_long ]

The others (See also: Details of Error Code)

Initial Value

The trigger monitor function is invalid.

Remarks

The trigger monitor function is a function, that uses the device's own timer or the Windows's timer to monitor the change of the specified bit's input value. When the input value of a bit changes from 0 to 1 or from 1 to 0, the change of the bit will be notified to the application through the Window message.

For USB device, it is only one process that can receives the trigger message.
The message cannot be sent from the same device to two or more processes.

The message ID is defined with DIOM_TRIGGER = 1340H. When the trigger occurs, the DIOM_TRIGGER message is posted to the specified window handle through the PostMessage function. The parameters of the message are wParam and lParam containing the following information respectively.

LOWORD(wParam)=ID retrieved from DioInit
LOWORD(lParam)=Trigger bit number
HIWORD(lParam)=Rising edge: 1, Falling edge, :2, Both sides: 3
* HIWORD indicates the high-order word. LOWORD indicates the low-order word. For details about message handling, please refer to the sample programs of each language.

To monitor the trigger for more than one bit, call this function for each corresponding bit.
When this function is called for each bit, monitoring is performed at the minimum value among the periods of trigger monitor set for devices.

This function cannot be used with DIO-CPS-BXC200.

For Ethernet devices
    If communication with the device is lost, the process will be unregistered and will no longer receive event notifications.
    If you want to perform event notification again, please make the settings again using this function.

     You can check the registration status of the current process using the DioGetNetCommunicationInfo function.

Example

The rising edge of logical bit 0 is monitored at 1000msec interval.

See Also

DioStopNotifyTrg DioGetNetCommunicationInfo