We were able to see where after connecting the PLC bombards the WeighTronix with identity requests then the connection times out.
Can you quantify or describe "bombards" ?
Are they CIP messages to read the various Attributes of the Identity Object (Class 1, Instance 1)?
Are you certain they are from the PLC, or might they be a "List Identity" broadcast packets from an RSLinx station ?
There may be more than one problem here, like a flaky network cable or switch that causes timeouts and then there's an unreliable re-connection.
One problem you might be experiencing is an error that existed in RSLogix 5000 several revisions ago related to electronic keying.
Ordinary A-B devices allow electronic keying to be enabled, and that's what generates inquiries from the controller to the device about its Identity Object. I was always surprised to learn that those queries are done *after* the connection is established, not before (at least, they were 10 years ago).
But Generic Ethernet Modules shouldn't have electronic keying at all. There was a bug where if you created the Generic Ethernet Module, then deleted it, then re-created it at the same address, the electronic keying would get enabled with no way to disable it from the GUI.
The solution was to delete the module, save as *.L5K, re-create the *.ACD file, then re-create the module without making any typos/reconfig. And of course it was fixed in later software.
I think I found this problem in v16 or v17, but I don't recall for sure. You probably have at least v21, so this probably isn't the issue.
In my experience, the symptoms of that Generic Ethernet Module keying problem was a cycle of connect / inquire / disconnect because of keying failure... reconnect and repeat. The I/O connection would come up running every 3 to 5 seconds and the shut down after half a second. So the symptoms you are seeing are different.