Omron NT31C Reference Manual page 179

Graphs
1, 2, 3...
168
1. When the percentage value is negative
The following happens, depending on the setting for Display Sign:
• No check mark: The graph line is displayed as 0% (Display % is shown in
negative value).
• Check mark:
Displayed in the minus range
2. When the absolute value of the percentage value is in the range of 100% to
999%
If the percentage value enters the range 100 to 999% or –100 to –999%, and
the line projects out of the graph area, only the part of the line inside the
graph area is displayed.
If a check mark is set for Display %, the calculated percentage value is dis-
played.
3. When the absolute value of the percentage value is greater than 1000%
If the percentage value exceeds 1000% or enters the range below –1000%
and the line projects out of the graph area, only the part of the line inside the
graph area is displayed, as in (2) above.
If a check mark is set for Display %, the percentage value is displayed as
follows.
• ∗∗∗∗%
Data Logging Function and Background Function
The data logging function is a function for recording (logging) the displayed val-
ues internally.
Normally, the data sampled for a trend graph is not recorded internally, but by
using the data logging function it is possible to back track and display past data.
With the PT, the data logging function can be used for the data of up to 8 lines.
The maximum data quantity that can be recorded for each is 1440 points, and
when this limit is exceeded the data is deleted from the oldest points.
If the Clear Log touch switch has been set, the data can be cleared at any time.
The background function allows data to be sampled even while the trend graph
is not displayed.
Usually, with trend graphs, data is only sampled while the graph is displayed and
sampling is stopped when the screen is switched. By using the background func-
tion, sampling can be carried out even while the trend graph is not being dis-
played. The recorded data is displayed by back tracking when the trend graph is
displayed.
The background function can only be used in conjunction with the data logging
function, and the only data recorded is that for the data logging function. Howev-
er, since sampling continues while the background function is being used, the
processing of the PT may be delayed.
100%
Latest data
0%
Latest data
–100%
Section 2-10
50%
–300%