Varying input voltage refrigerator testing application

I am working on an application for refrigerator testing. One of the specs that we need to comply requires that we vary the input voltage, (ex. 127 VAC for a 120 VAC unit) through some sort of voltage regulator. The biggest unit we test has a 2 hp compressor with a max current draw of 18 amps. We would like to know what equipment we would need in order to accomplish this through a LabVIEW application that we are working on. We could do this through GPIB, serial, etc. Any help on this matter will be appreciated.

You might be right. I was think of one small 1.5 HP controller (Commander SE) we are using that is being powered by 1-phase 240 VAC supply. So I was thinking the motor was 1-phase, but actually it does the voltage chopping to create a 3-phase supply to the motor.
It may be possible to still use one where you just use 1 phase relative to ground, but I'm not sure, and I'm not an electrical engineer to be able to tell how to do such a thing. It may be worthwhile to ask them if such a thing can be done. Or look around for some other motor speed controller manufactures that make a 1-phase motor controller.
I'm sorry, but I don't know where else to look or be of any help.

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Variant Input Parameters with ActiveX Objects

I've created an ActiveX library that exports a variety of objects using Visual C++ Version 6.0. I'm testing the methods and properties of these objects using both LabVIEW and Visual Basic clients. The problem I'm facing is that when testing under LabVIEW, I can't access methods that expect a VARIANT input parameter. The declaration in C++ of one object's such method looks like this:
void CChassis::Configure (VARIANT config, int rate);
I can create the ActiveX object with both LabVIEW and Visual Basic. I can invoke methods that do not use VARIANT input parameters using both as well; but, when I create a second ActiveX Object (a CConfiguration) and use the LabVIEW Variant operator, my attempt to invoke Configure fails with a "No Such Interface (E_NOINTERFACE)" error. The invocation fails identically if I wire the CConfiguration directly to the Variant input, as well. If I instead create a constant VARIANT as an input parameter, my Configure method gets called, although the method recognizes that I passed an invalid object.
Using Visual Basic I can invoke the Configure method without problems while encapsulating a CConfiguration object within a Variant.
So my question is, have I found a LabVIEW error, or is my approach flawed? If my approach is flawed, where have I gone wrong? Thanks in advance! I'm using LabVIEW version 7.0.

Hi,
Have you tried to put in plain data or an object reference into your variant parameter?
I think plain data should work... for object references i don't know.
Some time ago, i also coded a small activex library, where i passed object references by parameters in delphi. I did not use variant parameters, but the real interfacedeclaration types (like IMyObject**). This worked fine. I also uses "dual" interfaces for the objects, which get passed by parameter. But i don't really know if this is helpfull for vb.
Finally, you can also use a workaround:
For each of your Objects, that you want to use from LabView and which you want to pass by a parameter, you
insert an new Property "int32 Object_Handle".
When an Object gets created, it ask a "ObjectHandleManager" (gets written by you) to get an own unique Object_Handle which it stores into its property "Object_Handle".
The ObjectHandleManager generates an new Object Handle and memorizes the Handle assoziated with the calling object's reference.
Now, at each time, when you want to pass a object reference to a library function of your self, you can pass the Object_handle as an integer value. In the called function, you can ask your ObjectHandleManager for the real ObjectReference.
But thats not a very comfortable workaround.

Variant input to a simulation subsystem in LVSim 2.0

I have a simulation subsystem that takes a variant as one of its inputs. This worked well for my purpose in Labview 7.1. I've now upgraded to LabView 8.0 and simulation module 2.0. The subsystem appears correct when opened, but when I use it in a simulation loop, the variant input appears as type void and connecting a variant to it causes an error. Is this an error with my VI or are variants no longer allowed in simulation subsystems?

Chris,
I see what you mean. I looked through the release notes and Help files but did not see any mention of the variant data type. I will see if R&D has a more definite answer.
Best Regards,
Message Edited by Doug M on 07-05-2006 07:35 PM
Doug M
Applications Engineer
National Instruments
For those unfamiliar with NBC's The Office, my icon is NOT a picture of me

PC-6023 MAX INPUT VOLTAGE

IN THE NAME OF GOD
I have a pci-6023E card and potentiometer . The ouput of the pot. is differential .
The (-)end is always 13.5 Volt and the (+) end is between 5to22 Volt. I connected the output of the pot. to the input of the card in dif mode and i could measure the output of pot( ie 13.5-(5to22) ) successfully.Is this a correct connection to the card?
The maximum working voltage of each input of the card , according to manual, is 11 volt, but my sensor (i.e pot.) outputs are 13.5 and (5-22) !!
I used BNC-2110 terminal in dif. mode for this exprement.
Please explain me that how the card can successfully measured this input?
Can this demage the card at ling time or not?
thanks
Edward. Hb.

Thanks Mr. Alan A
I am "434343" memeber.
I recive your response to my question about "Max input voltage of PCI-6023E" .But I have some questions.
According to the "Data Acquistion Specification- a Glossary by Richard House" ( Application Note 092):
"Maximum Working Voltage (signal+common mode)= the highest voltage level that can be input to board without saturating the input."
And according to your response:
"measuring a signal with higher common mode voltage than that(11V) might not accurate"
But in may experiment with a potentiometer (floating differntial source with (-)13.5V and (+) 5to22V),I could successfully measure the signal without saturating and without error (Max error is about +/- 0.02 volt)!!
I think that the maximum working voltage of PCI-6023E is greater then 11 volt??!!
or my measurement has a little error.
I think that I don't need to use a signal conditioning circuit.
Please Help me.
Thans again.
Edward Hb.

Please help on online test application

Hi all, i'm developing an online test application. I'm done with the login page and uploading the question and i choose to display all the questions to the user but i dont know how to insert in the database cos i used a while loop to display the questions and options so i'm confused.please help

Thanks for your response.the thing's dat i've already retrieved the questions and options from my sql table. I just want to submit to the database and its not that i dont know how to do that, i just dont know how to submit multiple entries at once cos i have sumthin like:
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SCXI-1120D input voltage protection:

Hello All,
I have a SCXI-1120D input voltage protection question:
the data sheet specified 250Vrms. Does it mean signal plus CMV only? What if my signal itself is has a large potential difference (thus not CMV) , say 20V? Will the SCXI 1120D be damaged?
Thanks
Feilong

Hi Feilong,
You are correct. The 250 Vrms refers to your signal plus the CMV. See Figure 3-2 on page 32 of the SCXI 1120D User Manual. The paragraph above Figure 3-2 also explains this. I hope this helps!
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Ima
Applications Engineer
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LabVIEW Introduction Course - Six Hours
Getting Started with NI-DAQmx

How do I tell a variant input that a string is coming in?

I'm just learning how to use LabVIEW, so my apologies if this is a simple/stupid question.
I'm trying a variant on a DataSocket Read VI that was supplied with LabVIEW (I'm running version 7.1). I've got the "data" output line tied into a string. The "type (Variant)" input is connected to a 1-D array of unsigned bytes. There is an error in the wire connecting the "data" output to the string element, though:
You have connected two termnials of different types. The type of the source is 1-D array of unsigned byte [8-bit integer (0 to 255).
The type of the sink is string.
All well and good. How do I change the type of the source to string? When I right-click on the source and select "Replace", I can't see anything in there that looks like a string that isn't a constant... that is, a string type. I'd appreciate any insight you can lend me on this.

In the strings pallete you an find the Empty string constant or just a string constant . Wire that to the input (type) connector and it should produce the string you want.
Or you insert a byte array to string function in the broken wire.
Regards,
André
Message Edited by andre.buurman@carya on 08-29-2007 12:05 PM
Message Edited by andre.buurman@carya on 08-29-2007 12:05 PM
Regards,
André
Using whatever version of LV the customer requires. (LV5.1-LV2012) (www.carya.nl)

I'm not able to set Analog Input voltages, etc

ok,
so i have an NI DAQ I/O card (NI PCI 6723, or something to that effect) and i'm trying to configure the channels for Analog Input signals.
when i try to choose any kind of setting for Anolog signal by:
>>drop DAQ Assistant vi onto the block diagram
>>>>choose Analog Input
>>>>>>>Voltage
i get this message "No supported devices found"
i thought since I have the I/O card, i should be able to configure channels for both input/output.
i also have ADAC card (from IOTECH) installed but when i look at MAX, i only see the DAQ card.
i'm really confused at this point. can anyone break things down for me ... what i'm doing wrong?
-r

stuartG,
you were right. so what i'm using for the input is a ADAC 5501MF from IOTECH
following their manual (http://www.iotech.com/productmanuals/adac_lvi.pdf) it says that the ADAC-LVi libraries can be located at "Functions->User Libraries" palette of labview.
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-r

Interested in finding out about using LabView in Networking Testing applications.

Networking Testing applications, such as:
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LV provides a lot of tools which make VIs remotely communicate and control through net easily,such as VI server ,datasocket,tcp/ip,opc etc.I do not have much experiences in the environment you decribed,but in the internet and general ethernet programming with LV is very easy and interesting.

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[email protected]
[email protected]
[email protected]
[email protected]

I am not really sure how to solve this problem, you might be interested in checking this example on Accesing Individual Decoded Video Frames - http://java.sun.com/products/java-media/jmf/2.1.1/solutions/FrameAccess.html
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Why does my test application quit (disappear) during testing?

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I wrote test application using CVI2009 under WinXP. The application runs fine but when I repeat test, the application quits around the 9th or 10th repeat. When I reload and run the application it would quit again around the 9th or 10th repeat. I do not have a clue of what is going on. I have attached error logs A80428Error.bmp and A80428ErrorLog.bmp. Would someone please help?
Than you.
Robert Mensah
Solved!
Go to Solution.
Attachments:
A80428Error.zip ‏10 KB
A80428ErrorLog.zip ‏128 KB

Hello Robert,
a couple of hints on your problem :
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Message Edited by Roberto Bozzolo on 03-05-2010 09:34 AM
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?

Theme Testing Application

Hello
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Try http://htmldb.oracle.com/pls/otn/f?p=40722:101
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Varying input voltage refrigerator testing application

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