安捷伦E3631A测量电压不准确该怎么办？

我正在使用GPIB在E3631A直流电源上设置电压。
这样做没有问题，但我注意到，当我进行测量时，电压会下降0.02V左右。
测得的电压与设定电压相差不多。我使用IVI-COM驱动程序编写了一个Visual Basic .Net程序来执行此操作。
我在Agilent E36XX电源的IVI-COM驱动程序库中提到了'example1'。代码段如下：'初始化驱动程序ividc.Initialize（“GPIB :: 2”，False，True，“Simulate = true”）
'id query = false，reset = true pout1 = ividc.Outputs.Item（“Output1”）'设置输出电压电平pout1.VoltageLevel = 1.645'测量输出电压measVal = pout1.Measure（IviDCPwrMeasurementTypeEnum.IviDCPwrMeasurementVoltage）首先，设置
电压电平无误地进行，显示器上的设定电压是正确的。
但是测量电压的命令会导致显示器上的电压发生变化，并且变量measVal中包含的测量电压也不准确。任何想法出了什么问题？Isaac



     以下为原文

  I am setting a voltage on the E3631A DC power supply using GPIB. There is no problem with doing that but I notice that when I take a measurement the voltage drops by a little, around 0.02V. The measured voltage differs from the Set voltage by that amount.

I use the IVI-COM drivers and wrote a Visual Basic .Net program to do this. I referred to 'example1' in the IVI-COM driver libraries for Agilent E36XX power supplies.
A segment of code is below:

            'initialise driver
            ividc.Initialize("GPIB::2", False, True, "Simulate=true")  'id query=false, reset=true

            pout1 = ividc.Outputs.Item("Output1")

            'set output voltage level
            pout1.VoltageLevel = 1.645

            'Measure output voltage
            measVal = pout1.Measure(IviDCPwrMeasurementTypeEnum.IviDCPwrMeasurementVoltage)

At first, setting the voltage level proceeds without error, the set voltage on the display is correct.           
But the command to measure voltage causes the voltage on the display to change and the measured voltage contained in the variable measVal is inaccurate.
Any idea what went wrong?

Isaac