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FINS Communications Section 9-5
9-5-2 Overview of FINS Communication Service
Basic Functions FINS commands can be received from other PLCs or computers on the same
Ethernet network by executing SEND(090), RECV(098), or CMND
(490) instructions in the ladder diagram program. This enables various control
operations such as the reading and writing of I/O memory between PLCs,
mode changes, and file memory operations.
Executing, from the host computer, FINS commands with UDP/IP or TCP/IP
headers enables various control operations, such as the reading and writing
of I/O memory between PLCs, mode changes, and file memory operations.
For example, it is possible to connect online via Ethernet from FINS communi-
cations applications such as the CX-Programmer, and to perform remote pro-
gramming and monitoring.
Upgraded Functions With the CP1W-CIF41, the following functions have been upgraded.
• The FINS communications service can be executed not only with UDP/IP
but also with TCP/IP, and it is even possible to use FINS communications
with both UDP/IP and TCP/IP together on the same network. Using
TCP/IP makes FINS communications highly reliable.
• Even if the IP address and UDP port number of the host computer (a
DHCP client computer) are changed, it is still possible for the host com-
puter to send FINS commands to PLCs on the Ethernet network and to
receive responses. When UDP is used, either the automatic generation
(dynamic) method or the IP address table method must be selected for IP
address conversion. When TCP is used, changes in IP address and TCP
port numbers are handled automatically.
• Multiple FINS applications (CX-Programmer and user-created application
programs) at the same computer can be connected online to a PLC via
Ethernet (using either TCP/IP or UDP/IP).
Note The message service does not guarantee that a message will reach the desti-
nation node. A message may be lost during transmission due to factors such
as noise. To prevent this from occurring when using message services, it is
common to set up retry processing at the node from which instructions are
issued. 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.
Ethernet
Ethernet Option Board
Ethernet Option Board Ethernet Option Board
IP
UDP or TCP
FINS
CP1L/H CPU Unit
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