R.6.31
Date Code 20111215 Reference Manual SEL-421 Relay
DNP3 Communications
Application Example
In this example, the polling method employed by the RTU DNP master is
polled report-by-exception. The master device normally polls for events only.
Once every 25 event polls, the master polls for Class 0 data (status of all
points). This polling method allows the master to collect data efficiently from
the IEDs by not continuously polling and receiving data that are not changing.
Testing
In this example, we can also use the TEST DNP command to substitute each
measured value with a static value that you can control. You can then examine
received values in the RTU or at the SCADA master to verify that each point is
reaching the proper destination.
TIMERQ I Ignore time-set request because IRIG-B is used for time syn-
chronization
DECPLA 1 Scale current, multiplying by 10 to send amps and tenths of
an amp. The relay would report a value of 10.4 as 104,
which would remain unscaled at the master.
DECPLV 2 Scale voltage, multiplying by 100 to send kilo volts, tenths,
and hundredths of a kilo volt.
DECPLM 2 Scale miscellaneous analog data, multiplying by 100 to send
whole numbers and hundredths. The relay would report a
value of 5.25 as 525, which would remain unscaled at the
master.
STIMEO 10.0 Select/operate time-out
DRETRY OFF Turn off data link retries
MINDLY 0.05 Minimum delay from DCD to TX
MAXDLY 0.10 Maximum delay from DCD to TX
PREDLY 0.025 Settle time from RTS on to TX to allow EIA-485 transceiver
to switch to transmit mode
PSTDLY 0.00 Settle time from TX to RTS off; not required in this
application
ANADBA 50 Analog reporting dead band for currents, 5 amps based on
DECPLA scaling factor
ANADBV 100 Analog reporting dead band for voltages, 1 kV based on
DECPLV scaling factor
ANADBM 100 Miscellaneous analog value dead band, based on DECPLM
scaling factor
EVELOCK 0 Event summary lock period (0–1,000 seconds)
MINDIST
a
OFF Minimum fault location to capture (OFF, -10000–10000)
MAXDIST
a
OFF Maximum fault location to capture (OFF, -10000–10000)
ETIMEO 10 Event data confirmation time-out in seconds
UNSOL N Unsolicited reporting disabled because polling is polled
report-by-exception
MODEM N No modem connected to port
a
MAXDIST must be greater than MINDIST.
Tabl e 6 . 18 SEL -42 1 Port 3 Example Settings (Sheet 2 of 2)
Setting Name Setting Description
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