Magtek MAGTEK User Manual download pdf (Page 74)

MagTek Communications Protocol, Driver Reference Manual

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.

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Magtek MAGTEK User Manual Page 74