Reply To: Re: DLR Device Level Ring


Hi David, it’s been a while.

Well I’m sure you have the basic understanding of what Device Level Ring (DLR) is. It’s basically a way to add single fault tolerance to your automation network so that in the event you lose a communication path the acting “ring supervisor” can recover your network.

Some of the benefits a DLR and ring supervisor will provide:

  • Helps prevent and manages network loops
  • Determines active or backup status
  • Verifies ring integrity
  • Reconfigures the ring to recover from a network fault
  • Performs ring diagnostics

To name a few. This is very similar in architecture to a traditional spanning tree protocol (STP). Some of the drawbacks I would say are the following:

  • Added cost due to your distributed I/O adapters requiring two Ethernet ports vs one (however it reduces the main switch size as fewer ports are needed here if at all).
  • You now have to route conduit/cabling from device to device which can be difficult in large distributed systems vs bringing everything back to your main control panel/switch.
  • Adds complexity to the network.

I’m sure there’s more that can be said, but thought I’d chime in for you here anyway.