How do I find the unknown IP address of a Modbus Serial-to-TCP Gateway?

Issue:
How to find the unknown IP address of a Modbus Serial-to-TCP Gateway?

Product Line:
EGX100
ETG100
EGX300
EGX150 (Link 150)
Com'X

Environment:
Internet Explorer
WireShark

Resolution:
The lost IP address of a Modbus Serial-to-TCP Gateway can be found by examining the
WireShark trace of the Ethernet TCP/IP communications using the following steps.
This method can also be used for mostly any ethernet-based device.

• Download WireShark from https://www.wireshark.org/download.html
• Launch WireShark
• Select the active Ethernet adapter on the PC to start the WireShark trace.
• Power-Cycle the Modbus Serial-to-TCP Gateway.
  When the Gateway reboots, it will send a Gratuitous ARP from the MAC Address with the IP address of the gateway which can be seen in the trace.
• Confirm this is the IP address by using an Internet Explorer browser to connect to the embedded web pages on the gateway.