In DNP3, double binary inputs are represented using the double-bit binary input object, those are linked together. It allows the outstation to send the status of the double binary inputs to the master.
|
State name |
Input A |
Input B |
Description |
|---|---|---|---|
|
0 INTERMEDIATE |
0 |
0 |
Transitioning between end conditions |
|
1 DETERMINED_OFF |
0 |
1 |
End condition, determined to be OFF 0 |
|
2 DETERMINED_ON |
1 |
0 |
End condition, determined to be ON 1 |
|
3 INDETERMINATE |
1 |
1 |
Abnormal or custom condition |
As per the implementation, state 1 and 2 can be defined as ON or OFF. State 1 corresponds to what would be reported as 0, and state 2 corresponds to what would be reported as 1, if double-bit binary inputs were not available and a single-bit binary input were used instead.
A double-bit binary input point may optionally generate an event whenever the state changes. Only a single event is generated, not two events, if both inputs change simultaneously or within a device dependent interval.
Event variation:
-
Without time – binary state will be reported without timestamp.
-
With absolute time – it will be reported with the exact time of the event occurrence.
-
With relative time – the relative time of the state changes of binary inputs, records the time difference from a reference timestamp. This helps in reducing the amount of data transmitted, as only the time difference (offset) from the reference time needs to be reported to the master.
Static variation:
-
Packed format – it reports the current value of a binary input state without status flag.
-
With flags – it reports the current value of a binary input state with status quality flag.