“Modbus TCP is easy to implement because it is based on a very simple message structure containing an IP address, function code and data registers,” explained Haldeman. “The registers can be in 16-bit ...

What if the IP structure matches the physical location, so 172.18.32.234 reflects a physical location in the second octet (172.18.0.0/16=admin) and the VLAN is the third octet (32=acct)?