R.6.34
SEL-421 Relay Reference Manual Date Code 20111215
DNP3 Communications
DNP LAN/WAN in the SEL-421
simple integer value. Scaling on the Ethernet DNP3 connection is subject to
the same limitations of the serial interface. The master should also be
configured to perform the appropriate arithmetic conversion on the incoming
value to display it in proper engineering units.
Set the default analog value scaling with the DECPL setting. Application of
event reporting dead bands occurs after scaling the incoming value with
10
DECPL
. For example, if you set DECPL to 2 and ANADB to 10, a measured
current of 10.14 amps would be scaled to the value 1014 (10.14 × 10
2
) and
would have to increase to more than 1024 or decrease to less than 1004 (a
dead band of 0.2 amps) for the relay to report a new event value.
As with the DNP3 serial connection, the NUMEVE and AGEEVE settings are
used to decide when to send unsolicited data to the master. The relay sends an
unsolicited report when the total number of events accumulated in the event
buffer reaches NUMEVE.
The relay also sends an unsolicited report if the age of the oldest event in the
buffer exceeds AGEEVE. The SEL-421 uses the same buffer capacities with
DNP LAN/WAN as through the serial connection, listed in Tab le 6.6.
Time Synchronization
Time synchronization is not supported for DNP3 over the Ethernet port.
However, it will accept messages that contain a Record Current Time
(Function Code 24) request and return a Null Response.
DNP3 Settings
The DNP3 protocol settings that become available for DNP3 on the SEL-421
Ethernet port are shown in Table 6. 20. The DNP3 protocol settings are for the
port assigned to the Ethernet port: PORT 5. Please keep in mind that any
settings for the SEL-421 DNP3 Ethernet port will not affect any DNP3 serial
port configuration or operation and vice-versa.
It may be useful to note a few parameters that are unique to configuring DNP
LAN/WAN:
➤ The ENDNP setting allows the user to enable or disable all
DNP3 sessions on the Ethernet interface.
➤ The DNPMAP setting enables the usage of custom DNP3 maps
to define the data/control maps for the DNP3 sessions. The
DNPMAP setting can have one of two values: AUTO or
CUSTOM. AUTO is intended for the SEL-2032, SEL-2030, or
SEL-2020 Communications Processor applications. With the
SEL-421, we recommend that you always use CUSTOM.
➤ DECPL indicates an exponential scaling factor, 10
DECPL
, to
multiply by the raw value to calculate engineering units. Thus
the default value of DECPL, 0, will still result in the raw value
being multiplied by 1 (10
0
).
Up to 10 sets of unique master station parameters can be configured for
implementation when the relay communicates with a specified DNP3 host.
These parameters include: DNPIPxx, DNPTRxx, DNPUPxx, UNSLxx,
PUNSLxx, DNPMPxx, and DNPCLxx, where xx is a master station number
from 01–10. These allow you to specify, for all communication sessions with
a particular master, whether or not to:
➤ enable or disable unsolicited reporting at power-up,
➤ enable or disable unsolicited reporting for normal operation,
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