Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

228 Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems
8.6.3 Time information elements
The following information elements from Table 8.15 are presented in this sub-section.
Symbol
CP56Time2a
CP24Time2a
CP16Time2a
Table 8.15 Extract D
Command information elements
Description
Seven octet binary time
Three octet binary time
Two octet binary time
CP56Time2a – Seven-octet binary time
Seven-octet binary time is used for clock synchronization. Note that although days of the
week are defined, these are not used and are set to zero.
7 6 5 4 3 2 1 0
Day of week = 0
Minutes
Hours
Day of month
Month
Year
Octet Range
1
0 .. 59 999 ms
2
3 0 .. 59 min
4 0 .. 23 h
5 0, 1 .. 31
6 1 .. 12
7 0 .. 99
CP24Time2a – Three-octet binary time
This is typically used for time tags of information objects. It is the first three octets of the
seven-octet binary time element.
7 6 5 4 3 2 1 0
Milliseconds ms
Minutes
Octet Range
1
2
0 .. 59 999 ms
3 0 .. 59 min
CP16Time2a – Two-octet binary time
This is used for elapsed times such as for relay operating time. It is the first two octets of
the seven octet-binary time element.
7 6 5 4 3 2 1 0
Milliseconds ms
Octet
1
2
Range
0 .. 59 999 ms