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Communications Test Section 3-11
3-11 Communications Test
If the basic settings (in particular the IP address and subnet mask) have been
made correctly for the EtherNet/IP Unit or built-in EtherNet/IP port, then it
should be possible to communicate with nodes on the EtherNet/IP network.
This section describes how to use the PING command to test communica-
tions with the EtherNet/IP Unit or built-in EtherNet/IP port.
3-11-1 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 in the ICMP.
The PING command is normally used to check the connections of remote
nodes when configuring a network. The EtherNet/IP Unit or built-in EtherNet/
IP port 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.
3-11-2 EtherNet/IP Unit or Built-in EtherNet/IP Port Operation
The EtherNet/IP Unit or built-in EtherNet/IP port automatically returns the
echo response packet in response to an echo request packet sent by another
node (host computer, or other EtherNet/IP Unit or built-in EtherNet/IP port).
An echo request packet can be sent to another node by issuing the FINS
command to execute the PING command from the PLC.
3-11-3 Host Computer Operation
The PING command can be executed from the host computer to send an
echo request packet to an EtherNet/IP Unit or built-in EtherNet/IP port. The
following example shows how to use the PING command in the host com-
puter.
Command Method
Input the following command at the host computer’s prompt ($):
$ ping IP_address(host_name)
The destination is specified by its IP address or host name. If the host name is
used, the host name must be defined in the /etc/hosts file.
Note The PING command is not supported by some host computers.
EtherNet/IP Unit
Ethernet
ICMP
IP
UDPTCP
Echo response
Echo request
Remote Node
(host computer or EtherNet/IP Unit)