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2. Specifying the Sample Count. The sample count (i.e. trigger count) is
specified by the size parameter (50) of the CONFigure command. This is
the most convenient way to specify the sample count since size is a required
parameter of CONFigure. TRIGger:STARt:COUNt can be used to
set/change the sample count without also changing the entire configuration
with CONFigure.
3. Additional Information. Additional information on trigger sources and
sample rates is found in Chapter 3 - "Understanding the Digitizer", and in
Chapter 4 - "Command Reference".
Dual Rate Sampling
This program demonstrates:
• how to set up the digitizer’s dual rate sampling function whereby
pre-arm and post-arm readings are taken at different sample rates.
• how level arming can be used with dual rate sampling
The digitizer pre-arm samples at 50 ns until the level of the input signal on
channel 1 reaches 5V. At 5V, the digitizer is armed and post-arm samples at
10 ms.
DUALSAMP.C
*RST;*CLS /* clear and reset the digitizer */
CONF1:ARR:VOLT (20),10,(@3) /* set 20 readings, 10V range */
ARM:SOUR1 INT1 /* set arm source 1 for level arming */
ARM:SOUR2 HOLD /* disable arm source 2 */
ARM:SLOP1 POS /* arm on increasing input signal */
ARM:LEV1:POS 5 /* arm at 5V (10V range) */
SENS:SWE:OFFS:POIN -10 /* set 10 pre-arm readings */
TRIG:SOUR DTIM /* set dual rate sampling */
TRIG:TIM1 50E-9 /* set sample rate for pre-arm readings */
TRIG:TIM2 10E-3 /* set sample rate for post-arm readings */
INIT /* put digitizer in wait-for-arm state */
FETCH? /* retrieve readings */
Comments 1. Dual Rate Sampling Periods. The dual rate sampling trigger source
DTIMer uses the internal timer sources. Thus, one sample period must equal
the reference period. In this program, the digitizer’s internal
20 MHz oscillator is the reference source. Therefore, one sample rate must
be 50 ns (1 / 20 MHz).
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