R.6.11
Date Code 20111215 Reference Manual SEL-421 Relay
DNP3 Communications
DNP3 in the SEL-421
The settings shown in Table 6.7 that follow DNPAOD are entered in a line-
based free-form format. An example of these settings is shown in the
Application Example on page R.6.27. You can program a custom scaling and
dead band for each point where indicated. If you do not specify a custom
scaling or dead band, the relay will use the default for the type of value you
are mapping. For example, if you enter 87 in Row 1 of the custom analog map
with no other parameters, the power in MW will be available as Object 30 and
32, Index 0 and the relay will use the default scaling DECPLM and default
dead band of ANADBM (Table 6.7).
Scaling factors allow you to overcome the limitations imposed by the integer
nature of Objects 30 and 32. For example, the relay rounds a value of
11.4 amps to 11 amps. Use the scaling to include decimal point values by
multiplying by a number larger than one. If you use 10 as a scaling factor,
11.4 amps will be transmitted as 114. You must divide the value by 10 in the
master device to see the original value including one decimal place.
You can also use scaling to avoid overflowing the 16-bit maximum integer
value of 32767. If you have a value that can reach 157834 you cannot send it
using DNP 16-bit analog object variations. Use a scaling factor of 0.1 so that
the maximum value reported is 15783. You must multiply the value by 10 in
the master to see a value of 157830. You will lose some precision as the last
digit is rounded in the scaling process, but you can transmit the scaled value
using standard DNP Objects 30 and 32.
Warm Start and
Cold Start
The DNP function codes for warm start and cold start reset the SEL-421 serial
port. These function codes do not interrupt protection processes within the
relay.
Testing
Use the TEST DNP command to test the data mapping from the relay to your
DNP master. You can use the TEST DNP command to force DNP values by
object and index number. Although the relay reports forced values to the DNP
host, these values do not affect protection processing or other protocol
Row 10
a
Last custom counter map; custom
counter dead band
b
(Example: 3,
6)
Index number from default
map; 1–32767
Row 1
a
Custom analog input map; custom
analog input scaling
b
, custom ana-
log input dead band
b
(Example: 3,
10, 6)
Index number from default
map; 0.001–1000.000: 1–
32767
•
•
•
Row 200
a
Last custom analog input map;
custom analog input scaling
b
cus-
tom analog input dead band
Index number from default
map; 0.001–1000.000: 1–
32767
Row 1
a
Custom analog output map Index number from default
map
Row 2
a
Custom analog output map Index number from default
map
a
Free-form setting row hidden if corresponding default map is enabled.
b
Optional. If not specified, defaults to value associated with point in default map.
Table 6.7 SEL-421 DNP Map Settings (Sheet 2 of 2)
Name Description Range Default
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