| int EnableNotification(cid, hWnd, wInTrigger, wOutTrigger) | |||
| int cid; | |||
| HWND hWnd; | |||
| WORD wInTrigger; | |||
| WORD wOutTrigger; |
The EnableNotification function enables or disables communications message posting. When enabled, the driver posts the WM_COMMNOTIFY message to the specified window. USER calls this function when an application calls the EnableCommNotification function (USER.245).
cid
Identifies the communication device.
hWnd
Identifies the window to receive the WM_COMMNOTIFY message. If this parameter is NULL, the function disables the notification.
wInTrigger
Specifies the minimum number of bytes to be received in the communication device's input buffer before receive notification is sent.
wOutTrigger
Specifies the maximum number of bytes to remain in the communication device's output buffer before transmit notification is sent.
The return value is TRUE if successful. Otherwise, the return value is FALSE.
The export ordinal for this function is 100.
The WM_COMMNOTIFY message has the following parameters.
| Parameter | Description |
| wParam | Specifies the communication-device identifier (the cid parameter). | ||
| HIWORD(lparam) | Not used; must be zero. | ||
| LOWORD(lparam) | Specifies the notification status. It can be one of the following values. | ||
| Value | Meaning | ||
| CN_EVENT | An event enabled in the communication device's event mask (specified by the SetCommEventMask function) has occurred. The application should call the function GetCommEventMask to determine what event has occurred, and to clear the event. |
| This status is sent when the communication device's event word changes. The application clears the appropriate event to ensure notification on subsequent events. | |
| CN_RECEIVE | At least wInTrigger bytes are in the communication device's input buffer, or at least 1 byte is in the input buffer. Additionally, no more have been received before the end of an internal timeout period. The number of bytes in the input buffer must be lower than wInTrigger bytes before this message will be sent again. |
| CN_TRANSMIT | Fewer than wOutTrigger bytes remain in the communication device's output buffer to be transmitted. The number of bytes in the output buffer must exceed wOutTrigger bytes before this message will be sent again. |
The communication device event may be a line-status or printer error. Applications can determine the cause by using the GetCommError function immediately after the GetCommEventMask function (USER.209).