Omron DeviceNet 3G8F7-DRM21-E, Руководство по эксплуатации

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Checking Events
Section 3-3
When Scanner SDK receives a request addressed to a registered object, that
request is automatically stored in the response queue in the DLL file. There is
a response queue for each registered object and the response is queued for
as long as there is free memory on the computer. The response should be
removed from the queue as soon as possible after it is received.
There are two methods for detecting reception of explicit request messages.
Refer to
3-3 Checking Events for information on detection methods.
Maintenance API
Functions Status Service API Functions
Status Service API functions are used to monitor errors during I/O or explicit
message communications and monitor the communications cycle time for the
Master function. Monitor error status when creating user applications and per-
form error processing as required.
Error Log Access Service API Functions
Error Log Access Service API functions read and clear the error log registered
in the Board. Refer to
3-10 Error Log Functions for details.
PC Watchdog Timer Service API Functions
PC Watchdog Timer Service API functions monitor operation of user applica-
tions by the Board. Refer to
3-11 PC Watchdog Timer Management Function
for details.
3-3 Checking Events
3-3-1 Board Events
The following table shows the kinds of events that occur in the Scanner SDK.
3-3-2 Checking for Events
There are two ways to check events in the Board. Use the method that is eas-
iest for your application and system conditions.
• Detecting events with Windows messaging
• Checking events by polling
Detecting Events with
Windows Messaging A Windows message is sent automatically when an event occurs. A thread or
window can be specified as the destination for the event notification. The noti-
fication can include event specific information such as the interrupt status or
reception data length.
When the user application receives the event notification, it will read (receive)
the event after preparing a data buffer to hold the event data.
When you use Windows messaging for event notification, the notification mes-
sage settings must be made in advance with the
SCAN_RegIrqEvtNotifyMessage(), SCAN_RegClientEvtNotifyMessage(),
and SCAN_RegServerEvtNotifyMessage() functions.
Event Description
Interrupt from Board This event occurs when an interrupt is sent from the Board to
the computer. (An interrupt control register must be set.)
Explicit client
response received This event occurs when a response is received from the server
after an explicit client request message is sent.
Explicit server
request received This event occurs when an explicit server request message is
received for a registered object.