7SR120 Technical Manual
Chapter 4 - Page 62 of 84 © 2017 Siemens Protection Devices Limited
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)
or 2 (Double Bit Input with status)
Change Event Variation reported when variation 0 requested: 1 (Double Bit Input Change w/o Time)
or 2 (Double Bit Input Change with Absolute Time)
or 3 (Double Bit Input Change with Relative Time)
Point
Index
Description
Default Change Event
Assigned Class
(1, 2, 3 or none)
Default Variation
Static Object 3
Default Variation
Event Object 4
0 CB 1 0,2 1 3
10 User DP Command 1 0,2 1 3
11 User DP Command 2 0,2 1 3
12 User DP Command 3 0,2 1 3
13 User DP Command 4 0,2 1 3
14 User DP Command 5 0,2 1 3
15 User DP Command 6 0,2 1 3
16 User DP Command 7 0,2 1 3
17 User DP Command 8 0,2 1 3
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.
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.
Binary outputs are by default NOT returned in a class zero interrogation.
Note, not all points listed here apply to all builds of devices.
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