16.20
SEL-400 Series Relays Instruction Manual Date Code 20171006
DNP3 Communication
DNP3 Documentation
Binary Outputs
Binary output status (Object 10, Variation 2) is supported as defined by
Table 16.8. Static reads of points RB01–RBnn, OCm, CCm, 89OC01–89OCdd,
and 89CC01–89CCdd respond with the online bit set and the state of the
requested bit. Reads from control-only binary output points (such as the data
reset controls RSTTRGT and RSTDNPE) respond with the online bit set and a
state of 0.
The relay supports control relay output block objects (Object 12, Variation 1).
The control relays correspond to the remote bits and other functions as shown
above. Each DNP3 control message contains a trip/close code (TRIP, CLOSE, or
NUL) and an operation type (PULSE ON, LATCH ON, LATCH OFF, or NUL).
The trip/close code works with the operation type to produce set, clear, and pulse
operations.
Control operations differ slightly for single-point controls compared to paired
outputs. Paired outputs correspond to the complementary two-output model, and
single-point controls follow the complementary latch or activation model. In the
complementary two-output model, paired points only support close or trip opera-
tions, which, when issued, will pulse on the first or second point in the pair,
respectively. Latch commands and pulse operations without a trip code are not
supported. An operation in progress may be canceled by issuing a NUL trip/close
code with a NUL operation type. Single output points support both pulse and
latch operations. See Control Point Operation on page 16.20 for details on con-
trol operations.
The status field is used exactly as defined. All other fields are ignored. A pulse
operation is asserted for a single processing interval. You should exercise caution
if sending multiple remote bit pulses in a single message (i.e., point count > 1),
because this may result in some of the pulse commands being ignored and the
return of an already active status message. The relay will only honor the first ten
points in an Object 12, Variation 1 request. Any additional points in the request
will return the DNP3 status code
TOO_MANY_OBJS.
The relay also supports pattern control blocks (Object 12, Variations 2 and 3) to
control multiple binary output points. Variation 2 defines the control type (trip/
close, set/clear, or pulse) and the range of points to operate. Variation 3 provides
a pattern mask that indicates which points in that range should be operated.
Object 12, Variations 2 and 3 define the entire control command: the DNP3 mas-
ter must send both for a successful control. For example, the DNP3 master sends
an Object 12, Variation 2 message to request a trip of the range of indices 0–7.
The DNP3 master then sends an Object 12, Variation 3 message with a hexadeci-
mal value of “BB” as the pattern mask (converted to binary notation: 10111011).
Read right to left in increasing bit order, the pattern block control command will
result in a TRIP of indexes 0, 1, 3 to 5, and 7.
Control Point Operation
Use the trip and close, latch on/off and pulse on operations with Object 12 con-
trol relay output block command messages to operate the binary output points.
See Section 10: Communications Interfaces in the product-specific instruction
manual for a complete table of object 12 controls available in that relay. Pulse
operations provide a pulse with duration of one protection processing interval.
Cancel an operation in progress by issuing a NUL trip/close code with a NUL
operation type.
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