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Communications Testing Functions Section 9-1
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9-1 Communications Testing Functions
The FL-net Unit provides two functions that allow communications with other
nodes to be tested.
PING Command The PING command is a common way to perform echoback tests on Ethernet
networks. The PING command can be executed to see if nodes are physically
connected properly and to be sure that IP address are set for the correct
Ethernet nodes.
Internode Testing Echoback tests with specific nodes can also be performed by setting parame-
ters in the PLC Interface Area and then manipulating specific bits in memory.
This type of internode test can be performed only for nodes that support the
FL-net message service.
9-2 PING Command
The PING command sends an echo request packet to a remote node and
receives an echo response packet to confirm that the remote node is commu-
nicating correctly. The PING command uses the ICMP echo request and
responses. The echo response packet is automatically returned by the ICMP.
The PING command is normally used to check the connections of remote
nodes when configuring a network. The FL-net Unit supports both the ICMP
echo request and reply functions.
If the remote node returns a normal response to the PING command, then the
nodes are physically connected correctly and Ethernet node settings are cor-
rect.
9-2-1 FL-net Unit
The FL-net Unit automatically returns the echo response packet in response
to an echo request packet sent by another node (host computer or other FL-
net Unit. An FL-net Unit cannot send an echo request packet however.
9-2-2 Host Computer
The PING command can be executed from the host computer to send an
echo request packet to an FL-net Unit. The method for using the PING com-
mand from a UNIX computer is given next.
Echo request
Echo response
Remote Node
(host computer or Ethernet Unit)
TCP UDP
ICMP
IP
Ethernet
FL-net Unit