User's Manual

Printer SupportChapter —5
198 700 Series Color Mob ile Computer User’s Manual
NPCP Printer Communications
All NPCP printer communications should be based on the following flow:
1 Use CreateFile(); to open the printer driver.
2 Use IOCTL_NPCP_BIND to bind a session with the printer;
IOCTL_NPCP_ERROR to check for errors on the bind to ensure suc-
cess; and IOCTL_NPCP_CANCEL to cancel any outstanding print
jobs.
3 Use IOCTL_NPCP_FLUSH to poll the printer to free up printer buff-
er resources. Use IOCTL_NPCP_FLUSH to poll the printer’s status. If
an error is reported by the IOCTL, then use IOCTL_NPCP_ERROR
to get the error and determine the correct recovery procedure.
4 Use WriteFile(); to write your data to the printer. Check for errors and
that all data were written. Use IOCTL_NPCP_ERROR to get the ex-
tended error. If the error is critical in nature, use
IOCTL_NPCP_CLOSE, followed by CloseFile(), to end the commu-
nications session. Start a new session, beginning with step 1 to ensure
proper printing. For noncritical errors display the error and retry the
operation.
5 After all data is sent to the printer, ensure that the printer continues to
print the report properly by polling the printer’s status. Use
IOCTL_NPCP_FLUSH to poll the printer’s status. If an error is re-
ported by the IOCTL, then use IOCTL_NPCP_ERROR to get the
error and determine the correct recovery procedure.
Sample Code
See sample code in the “\700C Dev Tools\Installable D rivers\Port
Drivers\Npcp\NPCPPrint\” directory for more details on printing, printer
communications and error code handling.