Discover devices IP address?

At our plant we have some barcode readers that communicate with control logix via ethernet. The software we use to configure them requires you to know the IP address before you can connect. Normally they are set to default or have come from one of two other networks we use in the plant but today I had one that I was unable to determine the IP address of. Does anyone know of a good way to find this. I have tried using wireshark and setting my network to automatically obtain IP but the only traffic I've been able to capture is the DHCP request searching 255.255.255.255. The Barcode readers are Datalogic 6300 series and i'm using the datalogic genius software.There may be a feature in the software that does this but if so I can't find it.

Hi,

Welcome to the forum. I haven't used Wireshark, but I have used something similar.

Would this help?
http://www.colasoft.com/mac_scanner/index.php?act=mac_scanner

The way I do this is to connect just my PC to an unmanaged switch, start Wireshark, then plug in the unknown device.

Virtually all devices perform a Duplicate IP Detect when they are first plugged into a network. This consists of sending an ARP request for their own IP address to see if there's a reply.

If you set the Wireshark display filter to "arp", it makes it easier to find these packets. If you know the MAC ID of the device, it should stick out.

An example, from plugging in a 1756-ENBT module (thus the Rockwell MAC ID):