Hey Guys - We are having a networking issue with an experimental machine in the automation industry. The problem stems from a RFID reader communicating ISO-15693 tag codes to our machine PLC. The reader is connected to the machine LAN switch via ethernet interface. I'll spare most of the details for now but after several reads, the reader stops transmitting the data to the switch. The telling sign that we know that this is happening is that the up/down lights on the switch will turn off on the port the ethernet cable is plugged into, but the lights remain lit on the ethernet jack on the reader. The same will happen when connected directly to a laptop; bypassing the machine LAN. My question is what are some circumstances where the lights on a switch will turn off but remain lit on the device?