Bit Complement in an Expression Node

I can use bit complement in a formula node but not the expression node. The
"~" tilde is the only text in the expression node. The error is "~#" with
# being the error. The input is a U8. Thanks in advance for any help.

Hi Catherine,
I've tried your suggestion earlier and tried it again after your
post but it still doesn't work. I am new to expression nodes so maybe my
syntax is incorrect. To do the same in C language I think it looks like
this: "a = ~ b;". I made a picture and a copy of the error. Let me know
if you see anything wrong. Thanks!
Error on line 1 is marked by a '#' character: "~#"
[Image]
Pat S.
cfpautx wrote:
> Hello Pat,
> The way to fix this problem is fairly simple, if you change your
> inputs and outputs to I8, u16 or I16 it will run correctly.
> Regards,
> Catherine Petronino
> National Instrument
> www.ni.com/ask

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Expression node bit shift

Is this a bug or am I just thinking about this wrong? The attached VI shows a U8 going through an expression node where the expression is "x << y". I've tried multiple versions of y and as soon as y becomes large enough to shift all the original 1's off the U8, the result becomes 0xFF instead of 0x00. I would assume that its intent was to match C's functionality since it matches C's syntax but this does not appear to be the case.
Any suggestions or is this a bug?
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Attachments:
expression_shift_issue.vi ‏11 KB

Hey Andy,
Thank you for contacting National Instruments. It does look like that is acting strangely. However, we do have a Logical Shift VI that I believe accomplishes what you are looking for.
On the Block Diagram, go to Programming>>Numeric>>Data Manipulation>>Logical Shift.
It takes two inputs, x and y, with x being the original number, and y being the number of bits you want to shift. It looks like it will clear out to 00 once all the bits have been shifted over.
Let me know if you any questions!
Regards,
Kevin H
National Instruments
WSN/Wireless DAQ Product Support Engineer

Expression node

What is the correct syntax for an exponent with the expression node?
I looked in LabVIEW help, and it looked like it was the '^' character,
except that doesnt appear to be correct:
The correct output should be 2, but LabVIEW returns 3.
Cory K
Solved!
Go to Solution.

Darin.K wrote:
That is easily in my top 2 or 3 LV pet peeves. I use exponentiation countless times and the next time I use bit-wise XOR in a LV text formula will be my first. Why couldn't LV be like every other program/language I have used and use ^ for exponentiation?
Define your definition of every other programming language!
There are Ada, Bash, COBOL, Fortran, FoxPro, Gnuplot, OCaml, Perl, PL/I, Python, Rexx, Ruby, SAS, Seed7, Tcl, ABAP, Haskell (for floating-point exponents), Turing, VHDL which do just as LabVIEW, Algol, Commodore BASIC which use a special symbol ↑, and some like Java who don't even have a special exponentiation operator, but require the call of a math library function.
BASIC, J, MATLAB, R, Microsoft Excel, TeX (and its derivatives), TI-BASIC, bc (for integer exponents), Haskell (for nonnegative integer exponents), Lua, ASP and most computer algebra systems do use indeed the ^ symbol, but in Bash, C, C++, C#, Java, JavaScript, Perl, PHP, Python and Ruby, the symbol ^ is used for the XOR operator and the LabVIEW formula node borrowed a lot of syntax from C and is in its current incarnation in fact a limited C syntax environment, so that leaves the ^symbol not available for the exponentiation anymore.
Also I would say that LabVIEW is indeed more a programming language and not a computer algebra system.
Rolf Kalbermatter
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a division of Test & Measurement Solutions

Bug typedef does not connect to expression node

Attached is a simple vi that tries to connect a typedef (in this case a double) to an expression node.
Since LV8 this is not allowed anymore.
We choose LabVIEW because it was possible to use it as a strict typed language. (one of the reasons).
We see that the developers go a long way to make the language so easy that it is too strict to allow typedefinitions to an expression node.
But it can also be a slip of the compiler of course.
attached are the example vi and the typedef.
please supply a patch because this makes it impossible for us to switch to LV8
greetings from the Netherlands
Albert Geven
greetings from the Netherlands
Attachments:
typedef does not connect to expression node.vi ‏7 KB
dbl typedef.ctl ‏5 KB

A workaround is easy but should not be necessary because the typedef is used to keep it a typedef.
Simply use an explicit type conversion in this case to [DBL], at least that was my guess....
but an explicit conversion already knows there is nothing to do so it does not help.
A typecast helps but sure that is not what I want, see picture below.
greetings from the Netherlands
Attachments:
typedef bug not solved by explicit conversion.JPG ‏5 KB

Windows 7 64-bit X-Fi PCI-Express Audio console

Hello,
I have a SB PCI-Express Extreme audiocard, and I recently installed Windows 7. I have the basic driver and I do have sound, but the full control suite of software, that included the audio-console and startup-console I had in XP that allowed me full control of my card I do not. Which is rather annoying, because there's much more functionality there.
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Re: Windows 7 64-bit X-Fi PCI-Express Audio console" http://forums.creative.com/t5/Sound-Blaster/SB-P7X-Series-Support-Pack-2-0-07-3-2009-AudigySE-Value-LS/td-p/53329
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Polynomial in expression node

I would like to enter the following equation into an Expression Node:
1 / ((1.376E-17*x^4) - (0.000000000000026254*x^3) + (0.000000000023901*x^2) + (0.0000000055134*x10) + 0.000000063412)
However, each time I try I get block diagram errors. I've tried removing spaces, parans, etc but have had no luck resolving the problem. Any suggestions on how to do this or is there a different function in LabView that would be more appropriate? Thanks.

Hi JHess,
what about rewriting the formula as:
1 / ( (a*x)+b)*x)+c)*x+d)*x+e )
with a to e your constants from left to right.
It's just a different representation of the same formula. Your formula maybe doesn't work because of the "^" - powers should have to be written as "**".
Using LabView primitives instead of the expression node may speed up your code as well!
Message Edited by GerdW on 02-05-2008 09:51 PM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Expression node line too long

Hi,
I have an expression node which is very long. How do I break it into multi-lines?
Thank you in advance.
Qing

Hi Lucither,
I tried but do not know how to do it. Instead I attached my images of VI to you in a Word document.
Thank you for help.
Regards,
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Attachments:
HelpNI.docx ‏55 KB

Application Express node missing

Hello experts,
I have installed SQL Developer v. 1.5.5 Build MAIN-5969, connected to my application owner, but I can't find the Application Express node.
Any tip?
Tks
Edited by: user12088893 on Oct 27, 2009 9:32 AM

Hi Tks,
Sorry for the late reply, this may not be of use anymore but someone else may get something from it.
Is your install of Application Express 3.0.1 or higher?
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Does unsigned 32-bit arithmetic work in formula nodes?

I am trying to generate some 32-bit patterns to control my instrument under test. The easiest way to assemble these patterns seems to be to put the bits together in a formula node by shifting and OR'ing. All of my LabView variables are defined to be U32, and the corresponding variables in the formula node are uInt32.
The problem is that whenever I assign a "1" to the most significant bit of a variable, the entire value is coerced to zero. What is happening? what might I be doing wrong? I checked all of the obvious things, such as incorrect data definition, etc. I tried putting together the pattern in various orders, and I narrowed the assignment down to its simplest form. However, I still cannot get a value of 1 into the most significant bit of the U32.
Is there a way around this problem?
Thanks,

Well I seem to have recreated your problem using the formula node (either that or we're both not doing something right).. Look at "out1".
The logical shift function works fine of course.
Message Edited by Bill@NGC on 07-30-2007 08:42 PM
“A child of five could understand this. Send someone to fetch a child of five.”
― Groucho Marx
Attachments:
shift fp.png ‏219 KB
shift bd.png ‏206 KB

Using an array with an expression node on a PDA

I'm having a problem deploying an application to my PDA (pocket PC 2003) when the block diagram has an array wired to an expression node.
When I try to build the exe I get the following error:
retrun is a missing VI or C file.
Attached is an example VI that produces the same error
Thanks for the help.
Eric
LV 8.2
PDA Module 8.2
Attachments:
Array w ExN.vi ‏11 KB

Hello,
This is an issue known prior to release - it is documented in the PDA Readme file:
Open the LabVIEW Readme files folder by selecting Start»All Programs»National Instruments»LabVIEW 8.2»Readme, and then open readme_PDA.html.
Search that html page for "expression node" (without quotes) and you should find this issue acknowledged as the 8th bullet under the section entitled "VIs and Functions Known Issues."
Best Regards,
JLS
Best,
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Undocumented features of the expression node

After investigating expression nodes in detail here, I stumbled on some undocumented features that could give your UIs some interesting new twists (if used in moderation!).
I have not fully explored all possibilities, so there might be more.
I have tested in it LabVIEW 4.0 through 2013SP1 and it seems to work everywhere. (Versions below 6i show some slight pixelation artifacts, but that can be ignored)
Look what it can do!!!!
LabVIEW Champion . Do more with less code and in less time .
Attachments:
HiddenExpressions.png ‏8 KB

Hornless.Rhino wrote:
Hey wow, you can see through to the block diagram. Better put a perspex plate over that, you don't want animals getting in there and gnawing on the wires.
Just duplicating the myRIO design, where you can see the "circuits" under a glass cover.
LabVIEW Champion . Do more with less code and in less time .

Problems with bit shift left in Formula Node

Hi,
Sorry but my English is not good.
I'm trying to execute a bit shift left in the Formula Node, but the shift left is not working as I expected.
uInt32 parametro[5];
float32 valorAmostra;
int16 indiceAmostra;
uInt8 indiceResposta;
int16 controle;
int32 valor;
int8 i;
for(i=0; i<5; i++)
parametro[i]=param[i];
valor = parametro[5]<<16 | parametro[4]<<8 | parametro[3];
controle = parametro[1]<<8 | parametro[0];
indiceAmostra = (controle & 0x3FF);
indiceResposta = (controle >> 10);
valorAmostra = valor & 0x7FFFFF;
valorAmostra = valorAmostra*(2.4/8388607);
if((valor & 0x800000) == 0x800000)
valorAmostra = valorAmostra*(-1);
the input param array is of the type uInt8, as I saw in other topics that does not shift with uInt8,
I copy the values of param array to parametro which is of type uInt32, but still did not work.
Testing the input param with the following values:
param[] = {10,14,10,0,16}
the valorAmostra returned is 0,00117188 when he should be 0,300003.
Can someone help me please?
Solved!
Go to Solution.

Portuguese:
Olá,
Existe um bug no LabVIEW para esta operação. Este bug deverá ser corrigido em versões futuras. Uma solução para esta situação é utilizar um int32 ao invés de um ulnt32.
Qualquer dúvida por favor entre em contato.
Obrigado.
English:
I investigated the problem you are having, and it turns out that it is a bug that has already been reported and documented. The work around for it is to use int32 rather than uInt32.
Thanks.
Luciano Borges
R&D Engineer
Pirelli Brazil

Complement with Airport Express?

Greetings,
I have a Cat6 cabled home. The outside internet is pulled inside to the laundry room on the first floor where it then disperses into 4 other rooms. I currently use a Netgear WNDR4500 1000GB wirelss router in this area to share, but unfortunatley upstairs the wireless signal has some interference over the 5G/2.4G.
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Bit Complement in an Expression Node

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