User Guide

Trends
Trends Reference
7
206 | 393
Siemens
User Guide Version 3.0
A6V10415471
Building Technologies
2017-11-30
NOTE:
An uninterrupted site connection with the management station is required.
Measured values may be irretrievably lost when the site is interrupted during data
recording. Therefore, online trend is not well suited for long-term secure data
recording.
Offline Trend
Offline trend data is used for long-term storage and retrieval of historical data for
the analysis of entire plants or single processes. With offline trend, data is recorded
directly in the automation station. You can retrieve data as needed or automation
stations can automatically upload the data. The data recording can be prepared in
advance using the engineering tool or you can create a Trendlog object from the
management station in the automation station (must be supported by the
subsystem).
You can create an offline trend to assign the outside temperature to the Trendlog
object in the automation station if you want to calculate energy consumption and
need the outside air temperature series for measured values. You can then
manually or automatically (periodically) upload the recorded temperature data to
store in the management station.
Phase 1: Record Offline Trend Data
Trend data is saved locally to the
Trendlog object in the automation
station.
Phase 2: Upload Offline Trend Data
Trend data is uploaded if:
● The maximum buffer size is
reached.
● The number of defined
entries is reached.
● Manually triggered by the
management station.
7.2.4 Trend Data Storage
Recorded trend data can be stored in three different locations:
● Offline Trendlog Objects: Offline trend data is saved in the automation station.
● Online Trendlog Objects: Contains the online trend data recorded and saved in
the management station.
● Archived Trend Database (not in version 2.0): Contains all recorded Trend data
moved previously to the archive database.
Offline Trendlog Objects
Offline trend data can be recorded and saved by Trendlog objects within the
automation and control system even when the management station is not
connected. The recorded data can then be saved in the trend database. Offline
trend data can be retrieved and displayed in the trends.
64°F
64°F
Trend Log Object
Automation Station
64°F
64°F
64°F
64°F
Trend Log Object
Trend DB
Management
Station
Automation
Station