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Using the Digitizers 43Chapter 2
Making Digitizer
Measurements
This section provides three examples that show ways to make digitizer
measurements and to retrieve data. The three programs are:
• Example: Sampling Using Immediate Triggering
• Example: Triggering Using Internal Level Trigger
• Example: Triggering Using External Triggering
Example: Sampling
Using Immediate
Triggering
This example uses an IMMediate trigger to begin the sampling
measurements on two channels and to retrieve the interleaved readings
from FIFO memory. Resetting the digitizer sets the data format to ASCII,
sample source to timer and trigger source to immediate.
*CLS
!Clear the status system
*RST
!Reset the digitizer
VOLT1:RANG 4
!Set ch 1 to 4V range
VOLT2:RANG 4
!Set ch 2 to 4V range
SAMP:COUN 20
!Set sample count to 20
(common to all channels)
SAMP:PRET:COUN 10
!Set pre-trigger count to 10
(common to all channels)
INIT
!Initiate measurements
DATA? 20,(@1,2)
!Read 20 readings from chs 1 & 2
Enter statement
!Enter readings into the computer
Example: Triggering
Using Internal Level
Trigger
This example use the internal level trigger to trigger from an input ramp
signal as it crosses zero. The example takes pre-trigger readings and post
trigger readings.
Resetting the module sets the data format to ASCii, sample source to TIMer
and trigger source to IMMediate. The sample interval and the trigger source
are changed from the reset setting.
Resetting the module also sets the trigger level to 0V and the trigger slope
to positive. Trigger level and slope commands are resent to reiterate the
level and slope of the trigger. In this case, these commands are redundant.
*CLS
!Clear the status system
*RST
!Reset the digitizer
VOLT1:RANG 4
!Set ch 1 to 4V range
SAMP:COUN 7
!Set sample count to 7
(common to all channels)
SAMP:PRET:COUN 3
!Set pre-trigger count to 3
(common to all channels)
SAMP:TIM 50e-6
!Set sample interval to 50 µsec
TRIG:SOUR INT1
!Set trigger source to a level on
channel 1
TRIG:LEV1 0
!Set the trigger level to 0V
TRIG:SLOP POS
!Set trigger slope to positive
INIT
!Initiate measurements
DATA? 7,(@1)
!Read 7 readings from ch 1
Enter statement
!Enter readings into the computer