QDAC2 Reading Incorrect Current Values

[brycelynn-bailey]

Hello, I am working on a measurement in Quantify where one of the parameters set is the 'DC constant voltage' of a QDAC2 channel (along with other instruments) then the current corresponding to the same QDAC2 channel is read and logged as one of the parameters to get. The problem I am having is the current I am getting is not the correct value. I have checked that the voltage set for 'DC constant voltage' is correctly output with a digital multimeter, as well as what the expected current I should be measuring is using a multimeter and SourceMeter unit.

qdac=QDAC2.QDac2("QDac2", "ASRL13::INSTR")
qdac._internal_triggers={'inner'}
qdac.channel(9).measurement(3,1,'high')
qdac.channel(9).read_current_A.delay_s = 3

meas_ctrl = MeasurementControl("meas_ctrl")
meas_ctrl.settables(qdac.ch09.dc_constant_V)
meas_ctrl.gettables(qdac.ch09.read_current_A)
meas_ctrl.setpoints_grid([numpy.linspace(0, 1, 11)])

The plots below are for a 1 megaohm resistor directly connected to a QDAC2 channel with a 50 ohm to ground blank cap on the other side of the resistor. The expected result is zero amperes of current at 0VDC, and approximately one microamperes of current at 1VDC. A few key problems to note are:

1. There is a current being measured at 0V.
2. The two different channels do not produce the same graphs.
3. One of the channels has a negative slope for sweeping from 0V to 1V.

QDAC2 Channel 1:

QDAC2 Channel 9:

[jenshnielsen]

@Anders-QDevil FYI