Unitech PA500 Scanner Interface and USI DLL Programming Guide

2. USI.DLL – Unitech Scanner Interface DLL

Note : For PA500 programming, it need to dynamically load DLL for using Unitech built-in DLL (Unitech will not provide *.H and *.LIB for compiler for mobile 5.0 OS), please refer to Chapter 7 for programming guide.

2.1.Register the application to the USI DLL

Function Description: Register the application to the USI DLL, so that the DLL can communicate with the application. It will also open and initial scanner port (COM2, for example) and set the scanner to the working mode. The application should call USI_Unregister to unregister from the DLL after done with the scanner.

Function call:

BOOL USI_Register(HWND hwnd, UINT msgID);

Parameter: (input)

hwnd: Handle of the window to which USI DLL will send messages to report all activities, including error messages, scan data ready, etc.

msgID: Specifies the message to be posted. DLL will post messages by calling: PostMessage(hwnd, msgID, msg, param).

The window procedure will receive custom message about msgID and wParam parameter can be one of the followings:

SM_ERROR_SYS:	Indicates a system error, which is caused by a call to the system
	function. Param contains the error code from GetLastEror().
SM_ERROR	Indicates an error. Param contains the cause of error, which can
	be on of followings:
SERR_INVALID_HWND:		Invalid window handle.
SERR_INVALID_MSGID:		msgID cannot be 0.
SERR_OPEN_SCANNER:		Open or initial scanner port failed.
SERR_CHECKSUM:		Checksum error in received
		packet.
SERR_DATALOST:		New scan data is lost because data buffer is
		not empty.
SERR_BUFFEROVERFLOW:Data buffer overflow. The default size is 4K bytes.
SM_REPLY	Indicates received a reply. All the responses from the scanner
	except the scan data will be notified by this message.
SM_DATAREADY	Indicates that scan data is successfully decoded and ready to
	retrieve.
SM_ACK	Indicates received a ACK.
SM_NAK	Indicates received a NAK.
SM_NOREAD	Indicates received a No-Read packet.

Note: Scanner port settings are defined in registry as described below:

[HKEY_LOCAL_MACHINE\SOFTWARE\Unitech America Inc.\Scanner\Settings] "COMPORT"="COM2:"

"BAUDRATE"="38400"

"STOPBITS"="1"

"PARITY"="None"

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