Rockwell Automation 1336T PLC Comm. Adapter, Series B, FRN 2.xx-3.xx - Manual (Page 251)

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Publication 1336 FORCE–5.13 –– September, 1998
To create a cascading trend:
1. Set up your first trend as normal.
2. Set up your second trend with the same information as the first
trend with one exception: you need to set the second trend to
trigger when either the Trend Select parameter for the first trend
is equal to Disable or the Trend Status parameter for the first
trend is equal to Triggered.
The order of the trends is important. If you set up Trend 3 as your
first trend and Trend 2 as your second trend, there is a 10 millisecond
delay before Trend 2 triggers and starts collecting data points.
However, if you set up Trend 2 as your first trend and Trend 3 as
your second trend, Trend 3 immediately triggers and starts collecting
data points. This is a result of the way that the drive updates the
parameters.
When the trend output is linked to the analog output and a chart
recorder is then connected to the analog output, you can view the
trend output. To help you find the starting point of the trend, look
for a negative spike followed by a positive spike. These spikes are
added automatically to indicate the oldest piece of sampled data.
If you want to take a look at the current data, you can read the real
time trend sample data. To do this, you should use the
DriveTrending portion of the DriveTools software.
You can also use a GPT to view the output data of a trend.
Looking at the Results of
the Trend