GE Industrial Solutions Control System Toolbox For Configuring the Trend Recorder - Manual (Page 10)

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Chapter 1 Overview GEH-6408A Trend Recorder
|22 ms|
| 3 * 22 ms |
Value
Time Axis
Signal Sampling for
Real-time Drive Trending
When trending from an Innovation Series

drive, signal values are collected in a
group of four at a time, at an average rate of 20 ms per group. The sampling strategy
is similar to the AcDcEx drive; however, instead of getting only one signal value at a
time, the Trend Recorder reads up to four signals simultaneously. This greatly
improves the effective sampling rate over that of the AcDcEx drive.
Data is collected from the AcDcEx drive one signal value at a time. The average
sample interval between signals is about 50 ms.
Block Collection
Refer to the section, Block
Collected Trends. Block collection is available in controllers and in the Innovation Series drive using
the Capture Buffer block and in other drives using the Circular List block. The data
is uploaded to the toolbox when the collection is completed. Block-collected mode is
for high speed trending. The only limit on collection rate is the execution rate of the
collector block.
It is not necessary to have the
configuration file loaded
while replaying previously
uploaded data. Block-collected trending requires that the configuration file, which contains the
collector block, be loaded in the toolbox while the trend is set up and also when data
is uploaded from the block.
.dca Files
The .dca file is a common data storage format used by many applications. It is
primarily used to store data collected by the Data Historian product.
The Trend Recorder can read these files in two ways:
•
Individually, where you specify the name(s) of the .dca files to load into the
Trend Recorder.
•
As part of a Data Historian Collected Trend, where you specify signals from a
particular Data Historian device and/or Data Historian collection. The Trend
Recorder determines the name(s) and location(s) of the necessary .dca files.