Not so very long ago every major vendor of relays, remote terminal units (RTU), meters and programmable logic controllers (PLC), to name but a few intelligent electronic devices (IED) used in substations, had their own communications protocol. What this often meant was that most of the IED’s were incompatible even at the physical layer interface as well as the communications protocol layer. Therefore, as was often the case some sort of protocol converter device was required to bring all of the IED’s onto a common physical network and perform the translation to allow everyone to speak a common application layer protocol. This resulted in expensive integration with often-poor performance because of the insertion of protocol converters. To remedy these woes utilities turned to the Electric Power Research Institute (EPRI) and along with IED manufacturers and leading utilities such as American Electric Power collaborated to develop the Utility Communications Architecture (UCA2.0) which is soon to be released as international standard IEC 61850. It provides a set of standards and specifications with a common application layer protocol to ensure everyone speaks the same language and several communications profiles with Ethernet at the physical layer to ensure everyone resides on the same physical network. This is because Ethernet brings with it a multitude of advantages:
- 10Mbps, 100Mbps, 1Gbps, 10Gbps and growing speeds!
- Support for fiber, copper and wireless media!
- Network redundancy and fault tolerant ring architectures per IEEE 802.1w Rapid Spanning Tree protocol
- Message Prioritization and Class of Service for real-time control per IEEE 802.1p Priority Queuing
- Virtual LAN’s which allows for traffic isolation and system security per IEEE 802.1Q VLAN
- Deterministic (yes that’s right I said ‘deterministic’) full-duplex operation with no collisions per IEEE 802.3x Flow Control (Modern Ethernet Switches which support IEEE 802.3x do not allow, nor support, nor experience collisions! Collisions are a thing of the past associated with Ethernet networks implemented using shared media hubs/repeaters.)
- Ethernet is the world’s most widely adopted local area network (LAN) technology and is now migrating into the wide area networking (WAN) space. In the future we could see a total Ethernet solution from the WAN to the MAN (Metropolitan Area Network) to the LAN.
- Every major manufacturer of IED’s (e.g. Relays, RTU’s, Meters, PLC’s) now provides at least one (some provide dual) Ethernet port on their devices.
In the process control industry (i.e. industrial automation) a similar transformation has taken place with every major vendor of process control IED’s now providing Ethernet connectivity to the degree that many have espoused the notion that “Ethernet is becoming the RS232 for process control…”
