cast string to single precision

[ursb@my-deja.com]

Hi,

I try to write a communication between a PC and a DSP which is
programmed to
understand some kind of ModBus. I tried to use MBmaster.vi, a freeware
of AIRtech in the netherlands.
I was successfull to 90% after a very short time - I get back a string
from the DSP which makes sense.
The only problem is to *convert* the 4Byte=8Hex=32Bits(=IEEE754 single
precision format) into the LabView single precision number it does
represent .

In other programming languages like C I think I could do this easily
on a very low level procedure or with one of these dangerous casts.
As a newbie to LabView I could not found neither one VI to do this or
find out which simple combination of VIs could solve the problems.

Are there any cracks
here who know *the* easy solution??

Thanx & Regards
Urs Bögli

[Doug (CapeFl)]

Did you check the VI functions under Functions>String>Additional String to Number Functions?
There are quite a few for converting to/from Hex, etc. I've used them for concatenating 4-bit strings into an 8-bit string (to get an 8-bit byte/word), also converting to/from Hex using some of the VIs I mentioned.
Good Luck, Doug

[ursb@my-deja.com]

"Doug (CapeFl)" wrote in message news:<5065000000050000001C310000-991728092000@quiq.com>...
> Did you check the VI functions under Functions>String>Additional
> String to Number Functions?
> There are quite a few for converting to/from Hex, etc. I've used them
> for concatenating 4-bit strings into an 8-bit string (to get an 8-bit
> byte/word), also converting to/from Hex using some of the VIs I
> mentioned.
> Good Luck, Doug

Dough,
as a programmer for twenty years I have some problems to understand the way
labview does work with types and casts - other languages are much clearer about it
- or have I not found the ultimative help area yet ???

May I ask you to send me the VI off list?

thanks
Urs

[JeanPierre]

The Type Cast function is located in the palette Functions/Advanced/Data
Manipulation.

Wire the 4 bytes string to the "x" input and a SGL number to the type input.
It will output the string type casted to a SGL number.

Jean-Pierre Drolet

[EricE]

Urs,

I think the best approach would be to use the type casting vi. This is found on the function palette under advanced -> data manipulation. You simply wire in the string into the "x" input, an SGL integer into the "type" input, and the resulting "*(type*)&x" output should be in the format you want. Additionally, the string/number conversion vi's can be very helpful as well.

Best Regards,

Eric Enger

[ursb@my-deja.com]

Eric,
thanks a lot for this hint. After I ve brought the information into
the correcr order(lsb was at the start first...) I only had to add the
cast VI - thats simple and stupid, but not too much 😉
Best Regards
Urs



> Urs,
>
> I think the best approach would be to use the type casting vi. This
> is found on the function palette under advanced -> data manipulation.
> You simply wire in the string into the "x" input, an SGL integer into
> the "type" input, and the resulting "*(type*)&x" output should be in
> the format you want. Additionally, the string/number conversion vi's
> can be very helpful as well.
>
> Best Regards,
>
> Eric Enger

[Doug (CapeFl)]

Urs, based on all the other helpful inputs, there is a solution, in fact, more than 1.
I've attached a vi that should fit various needs, or at least give some clues...
Doug