How to find external device's subnet when IP is known?

asked 2018-06-28 18:39:38 +0000

Hi all,

Ignore my ignorance if it shows.. I've tried the best I could for the last few days, but I've had no luck. And this is pretty out of my depth.

In short, I bought a used Cognex camera off of a local business that decommissioned a warehouse, powered it up, all looked good, but the camera's software explorer couldn't find it. I assume that someone disabled the DHCP on the camera and switched it to a static IP.

Using wireshark, I found the static IP locally via a broadcast (It's, so I changed my ethernet IPv4 to be close to it (, and the subnet mask as ( But the camera can still not found and I get a "host unreachable" when I try to ping the device via cmd.. i think the subnet mask is wrong? I've read that there's a way to find the range, and tried, but I couldn't figure it out. Could something else be the issue?

Thanks for the help ahead of time, Christian

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I would say something else is the issue.

Maybe there's a way to factory reset the camera and start from there? Have you looked on Cognex's website for support for this camera? I have no idea which camera you have, but at least for "In-Sight 8000 Series Vision System", DHCP is the factory default. (See the Network Communication entry on the Specifications table on page 22 at

cmaynard gravatar imagecmaynard ( 2018-06-28 19:16:42 +0000 )edit

Thanks for the reply. Its an older Insight 5400 model (no crossover needed). I'm trying to figure out if there is a factory reset possibility. What makes you think that its something else and not the subnets being wrong?

chgeorge gravatar imagechgeorge ( 2018-06-28 19:28:01 +0000 )edit

Just curious.....if you clear your PC's arp cache and ping it again, does the camera respond to the ARP request of your pc? Also, do you see any ARP requests coming from the camera?

Rooster_50 gravatar imageRooster_50 ( 2018-06-29 00:00:00 +0000 )edit

Not sure if this is relevant to your camera or the software you're running, but have you tried the following, taken from

Tip: If the device does not automatically appear in the list, right-click within the list and select Show All Devices to display the local emulator and all In-Sight devices that support Ethernet configuration.

cmaynard gravatar imagecmaynard ( 2018-06-29 02:08:41 +0000 )edit