topic Re: convert engineering string into a number in LabVIEW

convert engineering string into a number

ramiral — Tue, 19 Jul 2005 13:59:42 GMT

Hello,

How can I convert an engineering string into a number with a floating point without loosing precision ?

Thank you

Re: convert engineering string into a number

ramiral — Tue, 19 Jul 2005 15:02:49 GMT

Sorry for the draft but I'm looking for something tlike this :

Re: convert engineering string into a number

Dennis_Knutson — Tue, 19 Jul 2005 17:00:51 GMT

Well, you've made a simple task fairly complicated. What's wrong with using either Scan String or Fract/Exp String to Number? Also, don't confuse the precision of the conversion with the number of digits displayed. Right click on a numeric indicator and select Format & Precision to change the display.

Re: convert engineering string into a number

ramiral — Wed, 20 Jul 2005 07:13:42 GMT

The last VI I have done is this one (see attached file)

In fact it's so easy with changing directly the format and precision!!! thank you 😉

Re: convert engineering string into a number

altenbach — Wed, 20 Jul 2005 07:58:04 GMT

What Dennis meant is that you can use "Fract/Exp String to Number" for everything, no need to jump through all these hoops!!! 😄

It can handle all kinds of inputs with full precisions (e.g. 1234, 4.5E-12 (upper case "E"), 1.23456789e12 (lower case "e"), etc.) The attached example shows a few possible inputs together with the numeric output formatted two different ways.

(You seem to convert all decimal points to commas, thus you probably use a non-US OS (German?). If all your strings have decimal points instead of commas, you can just disable the local decimal point in "Fract/Exp String to Number" as shown. Your version actually does not work correctly on an US computer, because the commas are not recognized as decimal separator here.)

Message Edited by altenbach on 07-20-2005 12:59 AM

Re: convert engineering string into a number

renault — Wed, 20 Jul 2005 08:47:50 GMT

Hello alten ,

out of curiosity i would like to know . How did you get two different formats of indicators (one in scientific and the other in floating ), connected to one terminal in the program 'convert engineering string into a number'.

regards

renault

Re: convert engineering string into a number

GerdW — Wed, 20 Jul 2005 10:12:22 GMT

Hello renault,

you can connect more than one data sink to a data source...

The formatting is done in the indicator (right click on the numeric indicator inside the arrays, properties or format&precision).

Re: convert engineering string into a number

renault — Wed, 20 Jul 2005 10:57:27 GMT

Thanks Gerd . got it .

Re: convert engineering string into a number

mikeporter — Wed, 20 Jul 2005 12:01:43 GMT

A really neat part is that all the stuff the other guys have been telling you about can also be done programatically using property nodes so if you are writing a GUI you could have an indicator change its format and precision based on the value its displaying...

Mike...

Re: convert engineering string into a number

Dennis_Knutson — Wed, 20 Jul 2005 13:22:41 GMT

And the winner for the LabVIEW code obfuscation is:

Re: convert engineering string into a number

altenbach — Wed, 20 Jul 2005 20:11:07 GMT

@altenbach wrote:

(You seem to convert all decimal points to commas, thus you probably use a non-US OS (German?). If all your strings have decimal points instead of commas, you can just disable the local decimal point in "Fract/Exp String to Number" as shown. Your version actually does not work correctly on an US computer, because the commas are not recognized as decimal separator here.)

As an additional note, remember that you can programmatically switch between period decimal and comma decimal format, by using the following silent formatting codes:

%,; --> Comma decimal separator
%.; --> Period Decimal separator
%; --> System default sperator

Check the online help for more details. 🙂

Re: convert engineering string into a number

Olli — Thu, 24 Apr 2008 15:48:40 GMT

Hello,
I just got a funny problem with the "Fract/Exp String To Number" function in LV 8.5. First a Windows feature, that was not known to me. I set the point as decimal separator in the regional options as usually. When my colleague logged in for the first time on this maschine the regional options were set back to default European
(with comma as decimal separator).
OK, here comes the problem with the "Fract/Exp String To Number" function: While I converted some DBL numbers in the VI into Strings and convert them back on another place (please don't ask why, I should change this immediately 😉 the "Fract/Exp String To Number" simply does not recognise the system's decimal separator even when the input "use system decimal point (T)" is left to default. Or could it be only my misunderstanding, that in this case it's meant as only "decimal point" and nothing else?
Ciao
Olli

Re: convert engineering string into a number

RavensFan — Thu, 24 Apr 2008 16:00:24 GMT

Yes. Regional settings are a function of which user is logged in. Each user can have their own settings. For a new user who has never logged in before, Windows sets their settings to some default. I'm not sure how you can change the defaults that Windows uses.

I'm not clear on exactly what your problem is. Can you post an example of the code you are using? Is it comma or period that is being used in the string? What is the regional setting for the user logged in?

Re: convert engineering string into a number

Olli — Fri, 25 Apr 2008 06:17:16 GMT

Hello Ravens Fan,
thanks for the reply! In fact I should have taken a cup of tea and thought it over before posting my question. The string I convert into a fractional number comes from another device. There the decimal separator is always a point not a comma....and so with the new regional settings of the new user the "Fract/Exp String To Number" function gave a correct output (by ignoring the point).
I will replace this function with the "Scan From String" function and specify the format of the number exactly, because this format will never change. Then it will be working with an regional setting of windows.
Ciao
Olli

Re: convert engineering string into a number

Olli — Fri, 25 Apr 2008 06:33:57 GMT

...or simply switch the "Fract/Exp String To Number" separator to "period"....I did not recognise this word as synonyme for the word "point".
OK this is time now for a strong coffee.
Greetings
Olli