And when a drawer is in place or replaced, the bypass switch opens. By installing separate bypass switches that close when drawers are taken out, you close the loop. A sub-system that “self-heals” after a unit is removed. There is one way of getting round – or bypassing – that constraint.

Daisy chain topologies are suitable only for fixed functional units that cannot be removed.īut in normal LV switchboard operations, there are always some drawers pulled out. What more can a switchboard ask for? A system that addresses any motor via two different paths and tolerates first faults anywhere on the sub-system. Tests show failovers take typically 500ms for DCLs with between 8 and 32 nodes (FUs). Should a switch fail, data will flow the other way. With two switches, you have redundancy, so the common mode is no longer an issue. It’s what we call a daisy chain loop (DCL) with a 2-switch ring. Unless you close the chain into a loop that circles back to another switch on the backbone. Because if you remove one FU, or it fails, you break the communication chain downstream. However, it’s only good for fixed functional units. In an LV distribution switchboard application, you can keep wiring to a minimum with the daisy chain configuration – for every column, just one cable in the cable tray. The daisy chain loop with the 2-switch ring An alternative is the daisy chain topology. Combined with a fault-tolerant backbone in ring configuration, it is a simple, fast, dependable solution – even in the most critical applications.īut all that wiring is a headache. A switch failure and all the nodes connected to it fail, too.Īnother drawback is the length and number of cables – there are as many as there are functional units in each switchboard column. The sub-systems depend on the switches they’re connected to. It’s what dependability studies call the “common mode”. There is a weak point, however, and it is do with redundancy. And FUs go on working even when others are removed Common mode impairs dependability In an LV distribution switchboard, it doesn’t care whether the mounting system is fixed, plug-in, or draw-out. It’s scalable and regardless of the number of FUs, it ensures very high-speed communication. Once the ring backbone is in place you can connect any number of nodes, or functional units (FUs), to the switches. Share Star topology fast, scalable, easy-going

Redundancy in network topology