Positive negative voltage sweep starting at zero

[craig_v]

Right to preface this i know nothing of the software im slowly learning however. 

I have an issue with the exe i have been given, when doing voltage sweeps the voltage starts at whatever number I put in first for example;

-5 +5 v 

This will start at -5v and not at zero is there a way i can change the original file to get the voltage to start at zero sweep up to -5 then +5 back to zero. 

I'm assuming I'm missing a very simple setting. 

Thankyou

Craig

[Gregory]

Hi Craig, we have no way to know what exe you have been given. The best way to get help is to post the VI (.vi file with code) that has been pared down if necessary to only show the area you are having a problem with. Once it has been built into an executable we can do very little besides guess at what the issue might be.

[craig_v]

I attached the code here, its designed for iv sweeps of devices (such as a resistor)

cheers for your help.

[Gregory]

Hi Craig, you want to go from 0 -> -5, then 5 -> 0
Your "voltage source A mode" control has options for single ramp and double ramp, but I think to accomplish what you want you will have to perform 2 single ramps. Is there a reason you want to break it up like this instead of going from +5 to -5V which will contain both of the sweeps you mentioned?

[altenbach]

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@craig_v wrote:

I attached the code here, its designed for iv sweeps of devices (such as a resistor)

cheers for your help.

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Wow, this code look about 20+ years old and has many very questionable features (error dialog not connected to anything, pointless stacked sequence, vestigial FOR loop, autoindexing on while loop output tunnels, Rube Goldberg boolean logic, 100ms wait outside the while loop (!!!) instead of inside, some labels with 2pt font, etc.). Is this really an example from HP or did somebody modify it? Maybe there is a newer version? I would not use this program for anything! Maybe you can extract the instrument IO and wrap it into a proper state machine while you fix the signal generation? Should be trivial.

[craig_v2]

Hi, as i had a new account it wont let me send more than 2 messages in a 24hr period so i just made a new one for the time being.

The reson i am wanting to start measuring at 0v is that the initial starting voltage has an effect on how the device im measuring functions (Im measuring memristors). Further i need the voltage to increase and remain ON for each concecutive measurment, i dont know if having 2 seperate ramps would do this. in between the 0>-5v and -5>0

Also from what i can gather this code is very old my supervisor made it years ago i dont know if modified it from an example or not, however i know hasnt changed anything since he made it years ago, he however overlooked the fact the starting voltage effects the results and i need to start at different voltages. 

I will look into what you mentioned however i have zero experience in this. 

Its funny because i have been using this softwear for over a year didnt realise it wasnt that great. 

[Gregory]

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@craig_v2 wrote:

in between the 0>-5v and -5>0

You originally said you wanted to go from 0 to -5, then +5 to 0. But, if it's 0 to -5, back to 0, then the double ramp should handle it.

[craig_v]

Sorry I think there is some confusion in the way I'm saying stuff;

I want the voltage to do the following.

0v>-5v>0v>5v>0v

So go through a total of 20v . 

[Gregory]

I see, it sounds like you'll have to do two double ramps, or find a way to program a custom ramp into your instrument.

[GerdW]

Hi Craig,

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@craig_v wrote:

I think there is some confusion in the way I'm saying stuff;

I want the voltage to do the following.

0v>-5v>0v>5v>0v

So go through a total of 20v . 

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Yes, there is some confusion: going from -5V to +5V is just 10V (peak-to-peak).

(You know the SI unit of voltage is "Volt", and its symbol is an uppercase "V" !?)