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Chapter 4) 7SR17 Rho - Data Communications
5.3.2 Double Bit Input Points
The default double bit input event buffer size is set to allow 100 events.
Double bit inputs are by default returned in a class zero interrogation.
Note, not all points listed here apply to all builds of devices.
Double Bit Input Points
Static (Steady-State) Object Number: 3
Change Event Object Number: 4
Static Variation reported when variation 0 requested: 1 (Double Bit Input w/o status)
Change Event Variation reported when variation 0 requested: 1 (Double Bit Input Change w/o Time)
Point
FW#
Index
0 CB 1
10 User DP Command 1
11 User DP Command 2
12 User DP Command 3
13 User DP Command 4
14 User DP Command 5
15 User DP Command 6
16 User DP Command 7
17 User DP Command 8
5.3.3 Binary Output Status Points and Control Relay Output Blocks
The following table lists both the Binary Output Status Points (Object 10) and the Control Relay Output Blocks
(Object 12).
While Binary Output Status Points are included here for completeness, they are not often polled by DNP 3.0 Masters.
It is recommended that Binary Output Status points represent the most recent DNP "commanded" value for the
corresponding Control Relay Output Block (CROB) point. Because many, if not most, Control Relay Output Block
points are controlled through pulse mechanisms, the value of the output status may in fact be meaningless. Binary
Output Status points are not recommended to be included in class 0 polls.
As an alternative, it is recommended that "actual" status values of Control Relay Output Block points be looped
around and mapped as Binary Inputs. (The "actual" status value, as opposed to the "commanded" status value,
is the value of the actuated control. For example, a DNP control command may be blocked through hardware or
software mechanisms; in this case, the actual status value would indicate the control failed because of the blocking.
Looping Control Relay Output Block actual status values as Binary Inputs has several advantages:
•
it allows actual statuses to be included in class 0 polls,
•
it allows change event reporting of the actual statuses, which is a more efficient and
time-accurate method of communicating control values,
•
and it allows reporting of time-based information associated with controls, including any
delays before controls are actuated, and any durations if the controls are pulsed.
The default select/control buffer size is large enough to hold 10 of the largest select requests possible.
Chapter 4 - Page 54 of 75
or 2 (Double Bit Input with status)
or 2 (Double Bit Input Change with Absolute Time)
or 3 (Double Bit Input Change with Relative Time)
Default Change Event
Name
(Description)
Default Variation
Assigned Class
Static Object 3
(1, 2, 3 or none)
0,2
0,2
0,2
0,2
0,2
0,2
0,2
0,2
0,2
© 2013 Siemens Protection Devices Limited
Default Variation
Event Object 4
1
3
1
3
1
3
1
3
1
3
1
3
1
3
1
3
1
3
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