I'm reading data from a couple of sensors using modbus via the RS485 port on a P2000 CPU. I have several identical machines doing the same thing. Recently, one of the machines has started giving me errors timeouts on the reads and the RX light on the port is now solid red. No programming has changed. No wiring has changed. Same machine with identical code as other machines that have been working for almost a year now.

I can take the sensors and put them on the other machines and they read just fine. I can take the sensors from other machines (working fine) and put them on the machine having the read issue and the reads do not work.

I can't find any information on what the RX light being solid red means. Anyone know?

Edited to add: the reads are timing out, not errors