User Manual
Chapter 4
GFK-2849A
Oct 2019
System Operation
82
IEC 61850 Client interface. This means that RX3i outputs to IEDs are sent synchronous to
the CPU sweep.
4.3.4
IEC 61850 Server Connections
The ECM850 connects with IEDs (IEC 61850 server devices) as an IEC 61850 client. The IEC
61850 client establishes associations with all configured IEDs. The ECM850 connects with
the devices and fetches data by polling at the configured polling rate or receives unsolicited
reports from the device based on the configuration of RCBs. These variable data are
available to the ECM850’s IEC 61850 client interface and is exchanged with RX3i CPU.
The IEC 61850 client interface operates asynchronously within the ECM850’s multitasking
environment, along with other firmware processes. The interface independently processes
the commands and messages for IEDs. Since the interface runs asynchronously, depending
upon how often IEDs send data and the CPU’s sweep period, it is possible that a
variable may
be updated more than one time by the IEC 61850 client interface before the RX3i CPU sees
the update. It may be possible in some cases that the ECM850 may not be able to transfer
every data change. Only the data most recently stored in the IEC 61850 client interface will
be available for the RX3i CPU. It is possible that some of the changes in variables in some
IEDs may be lost in the process, especially during times of high volume IED data traffic.
4.4
PPV Operations in RX3i Controller Applications
The IEC 61850 variables from the selected IEDs appear in the Machine Edition variable list as
PPVs. These variables can be used in the RX3i control application subject to normal variable
validation and download to the RX3i controller. The controller can be put in RUN mode to
run its application with IEC 61850 variables.
4.4.1
PPV Description
The PLC Protocol Variables, or PPVs, are variables available in the Machine Edition project
for use in RX3i controller application programs.
General Format of IEC 61850 Variables
The high-level IEC 61850 data model hierarchy for IED variables is shown below, depicting
the data model:
–
Physical Device (SR350)
–
Logical Device (GEDeviceSR350)
–
Logical cNode (LLN0)
–
Data Objects (Beh, Health etc)
–
Data Attributes (Q, stval, t).
The IEC 61850 Configurator displays the variables in the above format. The functional
constraints are shown in square bracket [e.g. [ST]/[CF] attached at the end of the variable
name.
