Operation Principle - ABB RES670 Technical Manual

1MRK 511 408-UUS A
19.6.3
Phasor measurement unit RES670 2.2 ANSI
Technical manual

Operation principle

The speed of the network depends on the medium and transceiver design. With
protection and control devices, fibre optic media is used, which enables the use of the
maximum speed of 1.25 Mbits/s. The protocol is a peer-to-peer protocol where all the
devices connected to the network can communicate with each other. The own subnet
and node number are identifying the nodes (max. 255 subnets, 127 nodes per one
subnet).
The LON bus links the different parts of the protection and control system. The
measured values, status information, and event information are spontaneously sent to
the higher-level devices. The higher-level devices can read and write memorized
values, setting values, and other parameter data when required. The LON bus also
enables the bay level devices to communicate with each other to deliver, for example,
interlocking information among the terminals without the need of a bus master.
The LonTalk protocol supports two types of application layer objects: network
variables and explicit messages. Network variables are used to deliver short messages,
such as measuring values, status information, and interlocking/blocking signals.
Explicit messages are used to transfer longer pieces of information, such as events and
explicit read and write messages to access device data.
The benefits achieved from using the LON bus in protection and control systems
include direct communication among all terminals in the system and support for multi-
master implementations. The LON bus also has an open concept, so that the terminals
can communicate with external devices using the same standard of network variables.
Introduction of LON protocol
For more information, refer to LON bus, LonWorks Network in Protection and
Control, User's manual and Technical description.
LON protocol
Configuration of LON
LON network tool (LNT) is a multi-purpose tool for LonWorks network configuration.
All the functions required for setting up and configuring a LonWorks network, is easily
accessible on a single tool program.
Activate LON Communication
Activate LON communication in the Parameter Setting tool under Main Menu/
Configuration/Communication/Station communication/ LON/HORZCOMM:1,
where Operation must be set to ON.
Section 19
Station communication
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