Eurotherm 6100, User Manual

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100/180MM DISTRIBUTED GRAPHIC RECORDER: USER GUIDE
Page 60 HA029324
Issue 11 Oct 14
4.3.2 GROUP CONFIGURATION (Cont.)
GROUP NUMBER
Allows a particular group to be selected for confi guration.
TREND UNITS
Allows mm/hr or inches per hour to be selected for the ‘chart’ speed. Automatically converts the trend
speed fi eld below.
DESCRIPTOR
Allows the group name to be edited. See section 3.3.1 for text entry techniques.
TREND TYPE
This allows the selection of Adaptive Recording for vertical and horizontal trend modes. The purpose
of adaptive recording is to ensure that rapid, short duration spikes (for example), are represented on the
‘chart’ even at low trend speeds. This allows the user to extend the total amount of history stored in the
recorder (by using slow trend speeds) without losing transient data.
The adaptive recording method works by measuring the input signal at the normal 125 msec period,
and saving the maximum and minimum values, continuously, over the period of trend update. When the
trend is updated, both maximum and minimum values are traced on the chart - i.e. two traces are pro-
duced for each channel in the group.
The faceplates and pen positions are still updated every second, as normal.
Notes:
1 During the period between updates, the maximum and minimum values are shown on the
trend as a horizontal line just beneath the pen, where the ends of the line represent the mini-
mum and maximum values so far. This line is removed at trend update time.
2. Adaptive recording takes twice as much memory as normal recording, so to maintain the total
amount of history stored, the trend speed must be reduced to 50% of that which would be
used for non-adaptive recording.
3. In Trend History mode, both minimum and maximum values for the cursor position are shown
on the faceplate. See section 3.4 for a description of trend history.
Figure 4.3.2b shows the difference between normal and adaptive recording, at slow trend rates. Note
that rapid changes in signal, (such as those shown in the circled area of the ‘actual signal’) are largely
fi ltered out by Normal Tracing, but is displayed by the Adaptive Trace. Figure 4.3.2b is for illustrative
purposes only, as traces such as these could never appear on the chart to gether.
Adaptive trace
Actual input signal
Normal trace
Max/Min
bar
Figure 4.3.2b Adaptive recording compared with Normal tracing