Measuring Modes; Overview - Omega Engineering OMB-NETSCAN 1500 User Manual

Appendix C

Measuring Modes

Overview

You can select either of two scanning modes for NetScan, 1) Normal mode or 2) High-speed, single channel
mode.
Mode "Average weight"
Setting
Normal
16, 32, 64, 128, or
256
1, 2, 4, or 8
High-speed,
not selectable
single-channel
In the Normal mode, NetScan samples channel data at 1.92 kHz, or once every 520.83 µs. You can select the
average weight (number of samples to average) to provide noise filtering, as discussed later in this section.
In the High-speed, single channel mode, NetScan collects data in user-defined multiples of 256 samples at a
sampling frequency within the range of 38.5 Hz to 20.0 kHz.
Aside from selecting NetScan's scanning mode, and setting the mode parameters from ChartView software (see
Chapter 4, ChartView Software Reference), the following commands can be used. Note that Appendix A
contains more detailed information regarding these commands.
Command Syntax
M# M#mode
W#wt
W#
F# F#freq
Y Ypre,post,stop
or
Y0,count,0
U16 M#modeF#freqW#wt
U17 U17
NetScan User's Manual
NetScan Measuring Modes
Application
Recommended for AC noise rejection.
Recommended for high-speed, multiple channel applications for thermocouples
and DC voltages where noise filtering is not an issue.
High-speed, single channel applications for AC and DC voltage post-acquisition
waveform analysis
Mode-Related Parameter Commands
Function
Set Measuring Mode.
Options for mode are:
0 - Normal mode, and
1 - High-speed, single channel mode.
Set Averaging Weight.
Specify the number of samples to average in Normal mode, where wt is the
averaging weight. Options for wt are: 1, 2, 4, 8, 16, 32, 64, 128, and 256, with 32
being the default.
Set frequency for High-speed, single channel mode.
freq must be a value for Hz such that 38.5 < freq < 2000. The default is 2000 Hz.
Set Counts or Select Blocks.
In Normal mode - This command is used to set acquisition counts where pre is the
pre-trigger count, post is the post-trigger count, and stop is the post-stop count.
In High-speed, single channel mode (burst mode) the post position serves as count.
count is used to select the number of 256 sample blocks to be collected. Options for
block count are dependent upon system memory as follows:
256Kbytes, count value allowed is: 2 to 512
1 Mbyte, count value allowed is: 2 to 2048
4 Mbytes, count value allowed is: 2 to 8192
8 Mbytes, count value allowed is: 2 to 16384
Note: In each case the number assigned for block count must be a power of 2.
Query the Measuring Mode.
This command queries the following three parameters: M#, F#, and W#.
Return RMS.
This command computes and returns the root mean square (RMS) value of the last
completed high-speed, single-channel mode acquisition.
Configuration Aspects for Programmers
C-3