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

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37
API Functions
Section 3-2
I/O Data Access Service API Functions
I/O Data Access Service API functions are used to read and write I/O data.
The PCI Board has two memory areas: the I/O area which can be read from
or written to using functions, and the Board’s internal buffer. Only the internal
buffer is used during I/O communications. Set to write all OUT data first,
refresh data between the two areas, and then obtain all IN data when I/O data
is to be used by user applications.
Slave Function API
Functions Slave Scan List Operation API Functions
To use the Slave function, information to enable operation as a slave must be
registered in a slave scan list. The Slave Scan List Operation API functions
are used to register a slave scan list. Refer to
Parameter Operation API Func-
tions on page 41 for information on the relationship between slave scan lists
and Slave Scan List Operation API function.
I/O Communications Service API Functions
I/O Communications Service API functions are used to temporarily stop/start
I/O communications with Masters when using the Slave function.
I/O Data Access Service API Functions
These functions are the same as the I/O Data Access Service API functions
for the Master function, but are used with the Slave function.
Explicit Message API
Functions Message Monitoring Timer Service API Functions
The message monitoring timer monitors the time from when a explicit mes-
sage request is sent until an explicit message response is received from the
remote node. If the response is not be received within the response time, the
request is timed out. The Message Monitoring Timer Service API functions
are used to set the message monitoring timer for each remote device.
The default message time is 2 s (2,000 ms). Set a longer time if the response
from the remote nodes will take longer. The next request to the same device
cannot be sent while waiting for a response.
Client Message Service API Functions
Client Message Service API functions are used to sent explicit request mes-
sages and receive responses, to set parameters for any device, and to moni-
tor information for that device.
When the Scanner SDK receives a response for the sent request, it automati-
cally stores it in the response queue in the DLL file. There is a response
queue for each remote device 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.
Noise or other interference may cause the explicit message to be lost. Also,
the message may not be received, depending on the remote device. Always
enable retries when sending explicit requests.
There are two methods for detecting reception of explicit response messages.
Refer to
3-3 Checking Events for information on detection methods.
Server Message Service API Functions
Server Message Service API functions receive explicit request messages and
send responses to implement any device profile.