Examining Trend Data With A Program Terminal - Allen-Bradley 1395 Troubleshooting Manual

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Examining Trend Data With
a Program Terminal
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The number of data samples taken after the trigger event is defined in
Parameter 914 "TR1 Post Samples". This parameter can be programmed
from 0 to 99. Each trend always consists of 100 data values. If the number
of post samples is less than 99, the remaining samples, minus 1 for the
trigger sample, will be taken before the trigger event occurs. For example, if
parameter 914 is programmed to 40 data samples, 59 samples will be taken
prior to the trigger event, the trigger event will be one data sample, and 40
data samples will be sampled after the trigger.
The trend function can be programmed to trigger once and hold that data
until the trend is enabled again, or it can be defined to capture data every
time the trigger occurs. This selection is made in Parameter 915 "TR1 Cont
Trigger". If OFF is selected, the trend will be executed only once, upon the
first trigger event. The trend will then be automatically disabled. The user
must enable the trend for another trigger to be allowed. If ON is selected,
multiple triggers will be allowed. Data sampling will occur with every
trigger until the trend is disabled. Previous data will be overwritten.
Before the trend can be executed, it must be enabled. If Parameter 916 "TR1
Enable" is programmed ON, the trigger event will be honored and data will
be sampled. If it is programmed to OFF, no data sample will occur. If no
links have been made to the "Trend X Input" configuration parameters, the
enable parameter will not allow ON to be programmed because no source
for the trend has been defined.
Data gathered via a trend can be examined in various ways including the
Bulletin 1300 Programming Terminal, PLC Block Transfer, PLC single I/O
transfer, and the Discrete analog output channel.
The Bulletin 1300 Programming Terminal uses main menu selection "8
Trend Files" to examine all data contained in a trend file. The next menu
allows selection of the desired trend file. After selecting the trend file
desired, the 1300 will retrieve the trend file information from the Bulletin
1395.
Under the "View Trend" menu header, the actual trend data values can be
examined by selecting "1 - Trend Data". The trend data is listed as data
elements numbered 0-99. The value of the sampled data appears to the right
of the data element number, and the time relative to the trigger, appears on
the top of the display. Moving through the data list is accomplished by using
various keys on the 1300 Programming Terminal.
Key Description
<0> Moves the cursor data to element 0.
<.> Moves the cursor to data element 99.
<+/-> Locates the cursor on the trigger element.
<INC> Moves the cursor ahead 10 elements.
<DEC> Moves the cursor back 10 elements.
<up arrow> Moves the cursor back 1 element.
<dn arrow> Moves the cursor ahead 1 element.
<1> Locates the cursor to the same element in Trend File 1
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Using Trending to Aid Troubleshooting 4-3