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FINS Commands with Host Link Protocol Section 3-5
Sending a Command from a Host Computer to PLC (A)
The following addresses are specified to the CPU Unit at network address 5,
node address 3:
Destination network address (DNA): 05 (30, 35)
Destination node address (DA1): 03 (30, 33)
Destination unit address (DA2): 00 (30, 30)
(Command addressed to CPU Unit)
Sending a Command from a Host Computer to PLC (B)
The following addresses are specified to the CPU Unit at network address 10,
node address 12:
Destination network address (DNA): 0A (30, 41)
Destination node address (DA1): 0C (30, 43)
Destination unit address (DA2): 00 (30, 30)
(Command addressed to CPU Unit)
3-5-4 Sending FINS Commands to the Host Computer from the CPU
Unit
With normal Host Link communications, FINS commands are sent from the
host computer to the CPU Unit. Commands can also be sent, however, from
the CPU Unit to the host computer. Any FINS command can be sent to the
host computer using SEND(090), which sends CPU Unit data to the host
computer, RECV(098), which receives data from the host computer, or
CMND(490).
Slave-initiated communications allows the host computer to be notified (unso-
licited communications) when an error is generated, for example, on a produc-
tion line controlled by a CPU Unit. Since the host computer no longer needs to
regularly communicate with the CPU Unit, the load on the host computer is
reduced.
When an Ethernet Unit or Controller Link Unit are mounted to the Backplane
of the CPU Unit, commands can be sent to the host computer from a CPU
Unit on a network on another level (up to three network levels).
Note In principle, send commands to the host computer only when one host com-
puter is connected to one CPU Unit. If more than one CPU Unit is connected
to the host computer, the commands may collide with each other and prevent
normal communications. Create a program that will exclusively control com-
mands that are being sent to a host computer to which multiple CPU Units are
connected.
Considerations when Sending Commands from a CPU Unit
Consider the following items when using instructions (SEND(090),
RECV(098), and CMND (490)) to send commands from the CPU Unit.
Host computer
Host Link
Controller Link, network address 5
Ethernet Unit
Node 10
Ethernet network, network address 10
Controller Link
Unit
Node 3
Ethernet Unit
Node 12
PLC (B)PLC (A)
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