Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

Fundamentals of distributed network protocol 135
Analog output objects
Time objects
• Analog output status data objects represent the actual value of the output
• Analog output block data objects are used to control the value of analog
outputs.The analog value they contain is termed the ‘requested value’. This
value may be scaled before being applied to the actual output. The actual
output value is returned by the analog output status data object
OBJECT GROUP RANGE 50 – 59, TIME OBJECTS
Group Var Type Description Structure
50
51
52
01 Not used Time and Date Time
02 Time and Date with Interval Time; T32
01 Time and Date CTO Time
02 Unsynchronised Time and Date CTO Time
01 Time Delay Coarse UI16
02
Time Delay Fine
UI16
• The time and date object is a 48-bit unsigned integer representing the elapsed
time in milliseconds since 00:00 hours on January 1, 1970. This and other
information element definitions are included in the Appendix
• The time and date with interval data object can be used to provide a starting
time and a repeat interval
• The time and date CTO (common time of occurrence) data object is used with
other objects that contain relative time references. Together they may be used
to efficiently determine absolute time
• Unsynchronized time is the time recorded at an outstation where the local
time has not been synchronized with the master station
• Time delay coarse is a time setting in seconds (0 to 65 535 seconds, ie up
to 18 hours)
• Time delay fine is a time setting in milliseconds (0 to 65 535 milliseconds,
ie up to 65 seconds)