Intermec CN2B Manual de usuario descargar pdf (Pagina 132)

Chapter 5 — Printer Support

114 CN2B Mobile Computer User’s Manual

• The port associated with the device during RegisterDevice() is in use.

• The NPCP device is already open.

• The share mode is not set to zero. The device cannot be shared.

• Access permissions are not set to GENERIC_WRITE |

GENERIC_READ. Both modes must be specified.

Closing the NPCP Driver

Using the CloseHandle() (hFile) function closes the NPCP driver. Where

hFile is the handle returned by the CreateFile() function call.

• TRUE = the device is successfully closed.

• FALSE = an attempt to close NULL HANDLE or an already closed

device.

Reading from the NPCP Driver

Reading of the NPCP printers is not supported since all responses from the

printer are the result of commands sent to the printer. DeviceIoControl()

functions are provided where data is to be received from the printer.

Writing to the NPCP Driver

All Print data can be sent to the printer using the WriteFile() function. The

print data written to the driver must contain the proper printer commands

for formatting. If the function returns FALSE, the NPCP error may be

retrieved using IOCTL_NPCP_ERROR. See the description on the next

page.

NPCP Driver I/O Controls

An application uses the DeviceIoControl() function to specify an printer

operation to perform. Certain I/O controls are required to bind and close

communication sessions with the printer, and must be completed before

any other commands to the driver can execute properly.

The function returns TRUE to indicate the device successfully completed

its specified I/O control operation, otherwise it returns FALSE. The follow-

ing I/O control codes are defined:

#define IOCTL_NPCP_CANCEL

CTL_CODE(FILE_DEVICE_SERIAL_PORT,0x400,METHOD_BUFFERED,FILE_ANY_ACCESS)

#define IOCTL_NPCP_BIND

CTL_CODE(FILE_DEVICE_SERIAL_PORT,0x401,METHOD_BUFFERED,FILE_ANY_ACCESS)

#define IOCTL_NPCP_CLOSE

CTL_CODE(FILE_DEVICE_SERIAL_PORT,0x402,METHOD_BUFFERED,FILE_ANY_ACCESS)

#define IOCTL_NPCP_ERROR

CTL_CODE(FILE_DEVICE_SERIAL_PORT,0x403,METHOD_BUFFERED,FILE_ANY_ACCESS)

#define IOCTL_NPCP_FLUSH

CTL_CODE(FILE_DEVICE_SERIAL_PORT,0x404,METHOD_BUFFERED,FILE_ANY_ACCESS)

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Intermec CN2B Manual de usuario Pagina 132