SSRC
242 Chapter 6 Command Reference
Power-on mode = AUTO
Default mode = AUTO
Remarks • For sub-sampling, the trigger event and the sample event are ignored. The only
triggering events that apply to sub-sampling are the trigger arm event (TARM
command) and the sync source event (SSRC command). For synchronous ACV
or ACDCV measurements (SETACV SYNC command), the specified trigger
arm event (TARM command), trigger event (TRIG command), and sample
event (NRDGS command) must all be satisfied before the sync source event
can initiate sampling.
• For sub-sampling and synchronous AC measurements, bursts of samples are
taken on more than one period of the waveform. The sync source event
synchronizes these bursts to the periods of the input signal (that is, a sync source
event should typically occur once for each period).
• Query Command. The SSRC? query command returns two responses
separated by a comma. The first response is the present source. The second
response is the present mode. Refer to "Query Commands" near the front of this
chapter for more information.
• Related Commands: LEVEL, LFILTER, SETACV SYNC, SLOPE, SSAC,
SSDC
Examples In the program on the following page, the SSAC command is used to digitize a
10 kHz signal with a peak value of 5V. The SWEEP command instructs the
multimeter to take 1000 samples (Num_samples variable) with a 2µs
effective_interval (Eff_int variable). The measurement uses the default level
triggering for the sync source event (trigger from input signal, 0%, AC-coupling,
positive slope). Line 120 generates a SYN event and transfers the samples directly
to the computer. Lines 240 through 410 sort the sub-sampled data to produce the
composite waveform. The composite waveform is stored in the Wave_form array.
10 OPTION BASE 1 !COMPUTER ARRAY NUMBERING STARTS AT 1
20 INTEGER Num_samples,Inc,I,J,K,L!DECLARE VARIABLES
30 Num_samples=lOOO !DESIGNATE NUMBER OF SAMPLES
40 Eff_int=2.0E-6 !DESIGNATE EFFECTIVE INTERVAL
50 INTEGER Int_samp(1:1000) BUFFER!CREATE INTEGER BUFFER
60 ALLOCATE REAL Wave_form(1:Num_samples)!CREATE ARRAY FOR SORTED
70 DATA ALLOCATE REAL Samp(1:Num_samples)!CREATE ARRAY FOR SAMPLES
80 ASSIGN @Dvm TO 722 !ASSIGN MULTIMETER ADDRESS
90 ASSIGN @Int_samp TO BUFFER Int_samp(*)!ASSIGN BUFFER I/O PATH NAME
100 OUTPUT @Dvm;"PRESET FAST;LEVEL;SLOPE;SSRC LEVEL;SSDC 10"
101 !FAST OPERATION, TARM SYN, LEVEL SYNC SOURCE 0V, POSITIVE SLOPE
105 !(DEFAULT VALUES) SUB-SAMPLING(SINT OUTPUT FORMAT), 10V RANGE
110 OUTPUT @Dvm;"SWEEP ";Eff_int,Num_samples
115 !2µs EFFECTIVE INTERVAL, 1000 SAMPLES
120 TRANSFER @Dvm TO @Int_samp;WAIT!SYN EVENT,TRANSFER READINGS INTO
121 !INTEGER ARRAY; SINCE THE COMPUTER'S INTEGER FORMAT IS THE SAME AS
125 !SINT, NO DATA CONVERSION IS NECESSARY HERE (INTEGER ARRAY REQUIRED)
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