CWIviDcPower AutoQueryFlags undeclared identifier

[RichMyers]

I am attempting to set the AutoQuery parameters of a Agilent E3631A DC Supply through IVI. The Measurement Studio Refernce indicates that I can use constants such as "cwividcpowerMeasCurrent" to set the values.

A couple of Visual Basic sample statements are also listed. I am using C++, and the SetAutoQueryFlags() method. It takes a long integer as an argument

void SetAutoQueryFlags(long nNewValue);

I tried to build a value using the constants, but I keep getting error C2065 : undeclared identifier.
The constants are not listed in the _cwividcpower.h header file. I cannot figure out where the constants are defined, or how I am supposed to figure out the value of the long integer I need to use as a paramat
er.
Can somebody point me in the right direction?

[Glenn Burnside]

The constant values are not defined as part of the exported interface for the control. However, you can pull the values from the control's property editor. I've included them below:
Query All: -1
Query ConstantVoltage : 1
Query ConstantCurrent: 2
Query OverVoltage : 4
Query OverCurrent: 8
Query Unregulated : 16
Measure Voltage :32
Measure Current :64

The values act as a bit mask, so yo can logical OR them together to query for multiple values.

If you're not using the control's interface in your UI, you might consider using the C++ Measurement Studio API supplied with the IVI Compliance Package 2.0 or later. This API integrates well with other Measurement Studio C++ API's, and might provide you with a more straightforward programming model
than the activeX control, which is intended primarily for use in VB 6.

[RichMyers]

Thanks Glenn. I had pieced together the constant values by changing the settings in the control's property page, and then using GetAutoQueryFlags() and a breakpoint in my program. I am not familiar with how I could "pull the values form the control's property editor". For future reference, can you explain further?

Also, with regard to using the C++ MS API, . . . I am afraid that I am a C++ newbie. I usually use CVI, but needed access to threads and return values from DOS command line executables. I have one C++ MS project under my belt where I achieved this. What is new to me on this one, is using IVI and a serial interface to a power supply.
I do not need the control's interface, but I have no idea how to get started with "using the C++ Measureme
nt Studio API" as you suggest. It took me quite a bit of effort just to stumble onto installing the IVI stuff and including the Active X control in my project. Could you point me in the right direction?

[Glenn Burnside]

I failed to mention a few details, I guess.

To find the possible parameter values, I opened up a VB6 project and added the DcPower control to the form. I then used the property grid to look at all of the possible values for the AutoQueryFlags property.

Before heading down the path of using the C++ API, I'd like to confirm your installation - you said you stumbled on to installing the IVI parts - what exactly did you install? Also, what version of Measurement Studio and Visual Studio are you using? I want to make sure the directions I give you are relevant and correct based on the software you're actually using. Also, if you're happy with using the ActiveX control from VC++, there might not be much reason to switch over to the power
supply's C++ api.

[RichMyers]

First, the SW versions:
Measurement Studio 6.0
C++ 6.0.0.105

As for the installations, things were not straightforward and I cannot remember all the details, but here's the synopsis:
1) Download and attempt install of HPE3631A driver, "hpe363xa_MS.msi" from ftp site. Noticed the requirement for IVI 2.1 or greater, and VISA 2.6.0 or better. I had VISA 2.6.0 installed, but IVI toolset was lower rev. Think I tried to run the hpe363xa_MS.msi installer anyway. [Hope springs eternal.]

2) Either the install failed, or I decided to update my SW versions. I downloaded and installed VISA 3.0.1, and I downloaded and attempted to install IVI Compliance Package 2.1, but the IVI installed failed. I entered a question in developers exchang
e
"IVI compliance package 2.1 install error 1714"
but eventually resolved the issue myself before I got a reply by repeatedly attempting to remove IVI 1.83, and then installing IVI CP 2.1.

3) After IVI CP 2.1 installed, ran the power supply .msi installation and opened Measuement Studio C++.

4) Figured out how to add the CWIviDcPower tool to the toolbox and dropped it in my dialog. Now I am working from there. [From your comments, it seems like I had another choice besides using the CWIviDcPower control.... and I am curious to know what/how that option is.]

All of this probably would take only a few hours for an experienced developer, or even less if the SW had already been up to date. But, unfortunately, I do not develop often, and usually use CVI. Plus, this is my first attempt at VISA & IVI. So, it took me a couple days to figure out and stumble through each step.

[Glenn Burnside]

With MeasurementStudio installed, using VC6, you should be able to go to the Measurement Studio toolbar and select the "Measurement Studio Add/Remove Components Wizard." This wizard will show you a tree of possible component categories. Under "IVI Class Drivers" you can select "IviDcPwr" - this will add the components to your project to allow you to code to the CNiIviDcPwr class, which is a c++ api wrapped over the IVI C interface. You can find help on this component in the Measurement Studio Reference, under the Visual C++ Help >> reference >> Instrument Drivers >> Class Drivers >> CNiIviDcPwr topic.