DMMSetACVSource. Signametrics SMX2040

measurem ent function. It actually sets an internal register to ldVols rather than setting the output level itself. This value is used on any of the AC Caps calibration and t is necessary to perform open calibration of the AC Capacitance ranges to be used. Since the DMM is optimized for the mmended not to use this function and keep the default 0.45V peak value.

Parame ter Type/Description

nDmm int Identifies the DMM. DMMs are numbered starting with zero.

Return Value

ldVolts

double Peak value of AC voltage to be set. Can be 0.1V to 5.0V

Integer error code.

Value

Meaning

DMM_ OKAY

Operation succe ssfully completed.

Example

Negative Value Error code

DMMSetACCapsLevel(0, 0.35); // Set source to 0.7V peak-to-peak

DMMSetACVSource

SMX2040 † SM X2042 † SMX2044 ;

Description

Set the ACV so urce output level and frequency.

#include "sm20 4032.h"

#include "User DMM.h"

int

nDmm, double FAR ldVolts, double FAR ldFreq)

function s ets the AC voltage source to RMS amplitude of ldVolts, and the frequency to ldFreq. The DMM must be in VAC_SRC operation for this function to execute properl y. When the DMM is i n VAC_SRC operation, and the

DMMSetACVSource is applied, reading the DMM (DMMRead, DMMReadStr) will return th e meas urement of th e output voltage. This function acts on the main 12 bit source DAC. If better accuracy is needed it can be accomplished by selecting the

ClosedLoop mode (DMMSetSourceMode). This mode engages the Trim DAC, which augments the 12 bit DAC to produce 16 effective bits. In the ClosedLoop mode, the source level is adjusted any time the DMM is read, making small corrections until the reading is equal to ld Volts. However, for the ClosedLoop mode to update the source level, it is necessary to read the DMM multiple times. Update rate should not exceed 5 rps when using the Closed Loop mode. Tw o ACV measurement ranges are available in

VAC_SRC mode, the 3.3 V and the 330 m V. If the Autorange mode is enabled, the

DMM will automatically s elect the appropriate range.

Return Value

Parame ter Type/Description

nDmm int Identifies the DMM. DMMs are numbered starting with zero.

ldVolts ldFreq

double FAR AC RMS voltage to be set. Range: 0.05 to 7.25 V RMS

double FAR DC voltage to be set. Range: 2 Hz to 76 kHz

Integer error code.

Signametrics 94