I’m trying to see if a PLC (Logix driver, but I’d like to know for any driver for future) lost comms overnight, but I don’t know which of the 100’s (1000’s?) of loggers to look at 
There reeeally needs to be some documentation of the loggers, not just for us the integrators, but also for support, as when I’ve spoken to them about it they’ve said that they basically have to go back on previous support cases to find which loggers to check…
It’s different for every driver because logger names are an implementation detail.
I have a far off future plan to solve this particular problem (some kind of way to get notified when a disconnect or other relevant event occurs) but that doesn’t help you now…
For the Logix v21 driver try com.digitalpetri.enip.ChannelFsm on DEBUG level.
You’ll see logging like this when the connection is lost:
D [c.d.e.ChannelFsm ] [22:59:36]: [10] channel idle, maxIdleSeconds=15
D [c.d.e.ChannelFsm ] [22:59:36]: [10] S(Connected) x E(ChannelIdle) = S'(Connected)
D [c.d.e.ChannelFsm ] [22:59:38]: [10] S(Connected) x E(KeepAliveFailure) = S'(Idle)
D [c.d.e.ChannelFsm ] [22:59:38]: [10] channelInactive() local=0.0.0.0/0.0.0.0:56398, remote=null
D [c.d.e.ChannelFsm ] [22:59:41]: [10] S(Idle) x E(GetChannel) = S'(Reconnecting)
D [c.d.e.ChannelFsm ] [22:59:41]: [10] S(Reconnecting) x E(GetChannel) = S'(Reconnecting)
D [c.d.e.ChannelFsm ] [22:59:43]: [10] S(Reconnecting) x E(ConnectFailure) = S'(ReconnectWait)
D [c.d.e.ChannelFsm ] [22:59:44]: [10] S(ReconnectWait) x E(ReconnectDelayElapsed) = S'(Reconnecting)
Perhaps a little different because this disconnect was caused by taking my VPN connection down, not by the other side actually doing a TCP close like a program download might cause.