int OpenComm(lpComName,wInQueue,wOutQueue)
This function opens a communication device and assigns an nCid handle to it. The communication device is initialized to a default configuration. The SetCommState function should be used to initialize the device to alternate values. The OpenComm function allocates space for receive and transmit queues. The queues are used by the interrupt-driven transmit/receive software.
| Parameter | Type/Description |
| lpComName | LPSTR Points to a string which contains COMn or LPTn, where n ranges from 1 to the number of communication devices available for the particular type of I/O port. | |
| wInQueue | WORD Specifies the size of the receive queue. | |
| wOutQueue | WORD Specifies the size of the transmit queue. |
The return value specifies the open communication device. If an error occurs, the return value is one of the following negative error values:
| Value | Meaning |
| IE_BADID | Invalid or unsupported ID. | |
| IE_BAUDRATE | Unsupported baud rate. | |
| IE_BYTESIZE | Invalid byte size. | |
| IE_DEFAULT | Error in default parameters. | |
| IE_HARDWARE | Hardware not present. | |
| IE_MEMORY | Unable to allocate queues. | |
| IE_NOPEN | Device not open. | |
| IE_OPEN | Device already open. |
LPT ports are not interrupt driven. For these ports, the nInQueue and nOutQueue
parameters are ignored, and the queue size is set to zero.