MagTek MAGTEK - Manual (Page 74)

MagTek Communications Protocol, Driver Reference Manual
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The following structure members are used as output parameters.
Member Meaning
dwApplicationID ID of the device application generating the notification
dwCommandID ID of the notification (application specific)
dwResultCode Result Code.
lpOutBuffer The buffer pointed to by this member contains the returned notification
data
dwResponseLen Length (in bytes) of notification data returned in buffer pointed to by
lpOutBuffer
Return Value
Value Meaning
MCP_ST_OK Success. Notification data is in the Output Buffer.
MCP_ST_NOT_FOUND No notifications found (valid only if dwTimeout was zero)
MCP_ST_TIMEOUT No notification arrived within the specifiec dwTimeout period
Remarks
This function can be used to retrieve the next notification message which the driver has received
and buffered from device. How the driver is to returned from this function call depends on the
dwTimeout member:
1) If one just wants to poll the driver to determine whether there are any notifications in
the queue, 0 would be specified so that the function would return immediately with
the next notification if one was queued or with an error code indicating that no
notifications were buffered.
2) If one wanted to retrieve the next queued notification or wait (for no longer than a
finite period of time) until the next notification arrives, a positive non-zero value
would be specified.
3) If one wanted to retrieve the next queued notification or wait indefinitely until the
next notification arrives, a "–1" value would be specified.
If the caller wishes to discard all queued notifications and only wait for the next new notification
message, the MCP_ATTR_WAIT_NEW flag should be set in the dwOperAttribute prior to
calling the McpWait function.