D.22
SEL-751 Relay Instruction Manual Date Code 20170927
DNP3 Communications
DNP3 Documentation
➤ Variation 245-TID setting
➤ Variation 246-RID setting
➤ Variation 247-RID setting
➤ Variation 248-Serial Number
Variation 249 shall contain the DNP subset and conformance, “2:2009”.
Variation 250 shall contain the product model, “SEL-751” and variation 252
shall contain “SEL”.
Binary Inputs
Binary Inputs (objects 1 & 2) are supported as defined by Table D.11. The
default variation for both static and event inputs is 2. Only the Read function
code (1) is allowed with these objects. All variations are supported. Object 2,
variation 3 are responded to, but contain no data.
Binary Inputs are scanned approximately once per second to generate events.
When time is reported with these event objects, it is the time at which the
scanner observed the bit change. This can be significantly delayed from the
time when the original source change occurred and should not be used for
sequence-of-events determination. Binary inputs registered with SER are
derived from the SER and carry the time stamp of actual occurrence. Some
additional binary inputs are available only to DNP. For example, STWARN
and STFAIL are derived from the diagnostic task data. Another binary input,
STSET, is derived from the SER and carries the time stamp of actual
occurrence. Static reads of this input always show 0.
Binary Outputs
Binary Output status (Object 10 variation 2) is supported. Static reads of
points RB01–RB32, OC/CC respond with the on-line bit set and the state of
the requested bit. Reads from control-only binary output points respond with
the on-line bit set and a state of 0.The SEL-751 supports Control Relay Output
Block objects (Object 12,Variation 1). The control relays correspond to the
remote bits and other functions as shown previously. Each DNP 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 Trip or
Close operations, which, when issued, Pulse On the first or second point in the
pair, respectively. Latch commands and Pulse operations without a Trip code
are not supported. You can cancel an operation in progress 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 for details on
control operations.
Use of the Status field is 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 can result in some of the pulse commands
being ignored and the return of an already active status message. The SEL-751
only honors the first ten points in an Object 12, Variation 1 request. Any
additional points in the request return the DNP3 status code
TOO_MANY_OBJS.
To Next Page
Loading...
