Set averaging weight – Measurement Computing TempScan/1100 User Manual
Page 255
TempScan / MultiScan User’s Manual
889897
API
Command Reference A-59
W#
- Set Averaging Weight
MultiScan/1200 only
TYPE
System
EXECUTION
Deferred
SYNTAX
W#wt
Specify the number of samples to average in line cycle integration / high-
speed multi-channel mode where
wt
is the averaging weight. Valid options
for
wt
are:
1
,
2
,
4
,
8
,
16
,
32
(default),
64
,
128
, and
256
.
DESCRIPTION
The Set Averaging Weight (
W#
) command selects how many samples to average for each thermocouple or DC
volts channel, or how many samples over which the Root Mean Square (RMS) is calculated for AC volts. When
the MultiScan/1200 unit is in line cycle integration/high-speed multi-channel mode with the default weight of 32
samples per channel, the unit can provide AC voltage, DC voltage, and thermocouple readings at a rate of up to
44 channels per second.
Further noise filtering is available with averaging over 2, 4, or 8 line cycles (at 32 samples per line cycle) by
selecting a weight of 64, 128, or 256 samples, respectively. If noise resulting from AC line pickup is not a
concern, you can program the MultiScan/1200 unit to average 1, 2, 4, 8, or 16 samples per channel for faster
scanning throughput.
Weight (wt)
Line Cycles (32 Measurements Each)
Maximum Number of Channels
1,2,4,8,16,32
1 744
64
2 431
128
4 234
256
8 122
For more information on MultiScan/1200 measuring mode parameters, see section Measuring Modes
(MultiScan/1200 Only) in the chapter System Configuration, and see commands Set Burst Mode Frequency (
F#
)
and Set Measuring Mode (
M#
).
Note: Due to hardware constraints, weights greater than 32 (default) limit the number of channels which can be
active in an acquisition.
Note: The MultiScan/1200 unit only supports the measurement of AC voltages where the frequency of the input
signal is an integer multiple of the AC line cycle. Consequently, sampling weights less than 32 can yield
incorrect results. In order to compute an accurate Vrms value, you must program a frequency which will
yield a sufficient even integer number of samples per line cycle.
EXAMPLE
PRINT#1, “OUTPUT07;M#0X”
‘ Select line cycle integration/high-speed multi-channel mode
PRINT#1, “OUTPUT07;W#64X”
‘ Select number of samples = 64
PRINT#1, “OUTPUT07;Y0,10,0X”
‘ Setup to read 10 Post-Trigger scans
PRINT#1, “OUTPUT07;C1-3,1X”
‘ Enable Channels 1 - 3 for Type J thermocouples
PRINT#1, “OUTPUT07;T1,8,0,0X”
‘ Arm the unit
PRINT#1, “OUTPUT07;@X”
‘ Trigger unit and collect scans