VTI Instruments EX1629 - Vtex1629_Get_Excitation

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EX1629 Command Set 155
vtex1629_get_excitation
FUNCTION PROTOTYPE
ViStatus vtex1629_get_excitation (ViSession vi, ViInt32 channel, ViPReal64 positiveExcitationVoltage,
ViPReal64 negativeExcitationVoltage);
FUNCTION PARAMETERS
vi = contains a session handle to the instrument. This handle is obtained by the function and remains valid until the
session is closed.
channel = an integer input value that specifies the channel for which the programmed excitation voltages will be
returned. Valid input values: 0 to 47.
positiveExcitationVoltage = a real return value, in volts, indicating the programmed positive excitation voltage for
a given channel. Valid return values: 0.000000 through 8.000000.
negativeExcitationVoltage = a real return value, in volts, indicating the programmed negative excitation voltage for
a given channel. Valid return values: -8.000000 through 0.000000.
DATA ITEM RESET VALUE
Not applicable to this function.
DESCRIPTION
This function queries and returns the actual excitation voltages for a given channel. The excitation value is quantized
with a 14-bit DAC. As a result, excitation value returned may be different from the value that was programmed
using the vtex1629_set_excitation function call. The total voltage applied to the bridge is equal to the positive
excitation voltage minus the negative excitation voltage. For example, if the positive excitation voltage is +5.0 V
and the negative excitation voltage is -5.0 V, the total excitation voltage is 10.0 V (5.0 - -5.0).
NOTE The control of the excitation voltage values and their enabling are disjoint operations. Thus, the
return of a nonzero value does not guarantee that the excitation source is enabled. That must be
queried with the vtex1629_get_excitation_enabled call.
EXAMPLE
ViSession instrumentHandle;
ViStatus status;
ViReal64 exc_pos, exc_neg;
…
status = vtex1629_get_excitation(instrumentHandle, 0, &exc_pos, &exc_neg);