Somat eDAQ
lite
74
I2773-4.4 en
NOTE
The maximum number of channels allowed for a group DVM display depends on the
display mode selected in the Group DVM Display Preferences. For more information
on these preferences, see “Group DVM Display” on page 57.
Notes on Run-Time Displays
Run-time data is acquired using two different methods depending on the display mode. The digital readout, bar chart and strip
chart displays use the min-max data acquisition method while the scope and spectrum plots use the contiguous block data
acquisition method.
Min-Max Method:
•
When the run-time display starts, the eDAQ
lite
continuously monitors each channel, tracks the minimum and
maximum signal values and holds those values in a buffer. Periodically, TCE polls the eDAQ
lite
to get the minimum
and maximum values. After the eDAQ
lite
sends the values to TCE, it resets the min-max search so that the next read
gives the minimum and maximum values since the last read.
•
A min-max display runs continuously on the eDAQ
lite
while the display is opened and examines all data samples in
the min-max search. Though the display was designed to minimize the overhead on the eDAQ
lite
, it does add to the
eDAQ
lite
processing load and can result in a DeviceOverFlow error reset for tests running at the edge of the eDAQ
lite
processing limit.
•
Minimum and maximum values are not time-stamped and the TCE polling loop results in reads that are only
approximately equally spaced in time. When using PC Card data storage, the time interval between TCE polls is
typically more erratic.
•
The min-max display mode can only be used with one application at a given time. If a second application (e.g., InField)
attempts to run a min-max display mode at the same time, the data presented in TCE becomes invalid.
Contiguous Block Method:
•
When the run-time display starts, TCE requests a contiguous block of data samples from the eDAQ
lite
for the selected
channel. The eDAQ
lite
responds to the request by returning the block of data samples. TCE displays the data in the
specified format and then requests a new block of data samples.
•
A contiguous block display adds to the eDAQ
lite
processing load and can lead to a DeviceOverFlow error reset for
tests running at the edge of the eDAQ
lite
processing limit.
4.5.2 Common Display Options
Start Run (run-time only)
For run-time displays during a preview run, select Start Run to start a test run.
Display Pre-Init Prerun Run-time Max Chs.
DVM yes yes no 16 or 256
Scope Plot yes yes yes 1
Spectrum Plot yes yes yes 1
Digital Readout no no yes 16
Bar Chart no no yes 16
Strip Chart no no yes 4
HBM: public
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