Omron CJ1W-FLN22, Руководство по эксплуатации, Страница: 118 / 277

Overview of FINS Communications Section 7-1
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7-1 Overview of FINS Communications
The FINS communications service enables client control of operations such
as reading or writing server PLC memory area data without the need to pro-
gram these operations into the server PLC user program. The FL-net Unit
uses FL-net message transmissions to execute the FINS communications
service. (Refer to
Vendor Message (FINS Message) on page 90.)
7-1-1 Communications On An FL-net (Ver. 2.00) Network
Data is sent and received as messages on an FL-net (Ver. 2.00) network.
Note A message may be lost during transmission due to factors such as noise. The
message service does not guarantee that a message will reach the destina-
tion node. To prevent this from occurring when using message services, it is
common to set up retry processing at the node from which instructions are
sent. With the SEND(090), RECV(098), and CMND(490) instructions, retry
processing is executed automatically by specifying the number of retries, so
specify a number other than 0.
7-1-2 FINS Communications Service Features
The FINS communications service is a function for controlling operations such
as sending and receiving data, changing modes, and so on, between nodes
on OMRON factory automation networks. It provides the following features.
• Communications instructions are executed in the user program.
• Writing data, changing modes, reading detailed information about Units,
and so on, can be executed without any particular knowledge of commu-
nications procedures or network classification.
Ethernet header
IP header
UDP header
FCS
FL-net (Ver. 2.00) message
OMRON PLC
FL-net Unit
or host computer
FL-net (Ver. 2.00) message (FINS command)
Ethernet
FL-net (Ver. 2.00) message (FINS response)
FL-net Unit
OMRON PLC
FINS frame
FL-net (Ver. 2.00) header