Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

140 Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems
Each of these objects is comprised of a sequence of four-bit BCD digits. There are 4, 8
or 16 BCD digits respectively for variations 1, 2 and 3.
BCD N BCD 2 BCD 1
3 Digit 0 … 3 Digit 0 3 Digit 0
The flag structure is as follows. This is the same as flag 4 shown in the Appendix.
7 6 5 4 3 2 1 0
Bit Interpretation
0 On-line
1 Restart
2 Communication lost
3 Remote forced data
4 Local forced data
5 Over-range
6 Reference check
7 Reserved
The DNP3 Basic Four documentation provides the following units code assignments.
As the code allows for up to 256 different codes, it is entirely possible that other codes
may be added over time and as required by users.
Units Code Key
0 Volts peak-peak
1 Amperes peak-peak
2 Volts RMS
3 Amperes RMS
4 Real Power kW
5 Apparent Power kVA
6 Reactive Power kVAR
7 Energy kWh
8 Imaginary Power kVARh
9 Power Factor pf
10
11
12
13
14
15
16
17
18
19
Frequency Hz
Frequency rad/sec
Temperature C
Temperature F
Temperature K
Force in Newtons N
Mass kg
Acceleration meter/sec squared
Pressure N/square meter
Torque Newton-meters
5.8.3 Key to data structure
General
DNP3 data objects have been constructed from a number of basic data types. Understanding
the shorthand notation for these data types assists in readily understanding
the structure of the various data objects, particularly if using the DNP3 documentation for
particular data objects.
Some key information has been included in the text at this point as a reference in interpreting
some of the information element descriptions. This information also appears in the
Appendix, with some additional details.
The following table of data types is repeated from the DNP3 documentation.