LabVIEW
convert hexadecimal output to decimal (number)
Coop wrote:
> I am reading hexadecimal format from the output of the VISA read block
> and I want to convert it to the decimal preferably exponential format.
> Example of what I read is 76 00 02 (in dec: 7.600 E+2).
> I know there is "type cast" block that converts nicelly but I am not
> sure what to specify for a type input.
> Can you show me how to apply this type cast block for in my VI so that
> it converts hex string (76 00 02) into exponential string/number
> (7.600 E+2)?
Looking at your code I see that you have not a hexadecimal string coming
back but instead a binary string. The fact that you display the string
as hexadecimal in the string indicator is just showing you the ASCII
codes of the string characters as hexadecimal numbers.
The funct
ion From Hexadecimal String expects a clear text string with
hexadecimal characters but that is something entirely different from a
binary string you choose to display as hexadecimal numbers.
An example: the binary string 7600 02 you receive from the device is in
fact the character 'v', a null character and a 02 character (or in ASCII
terms a start of text character).
So assuming your example is right (which I have to admit seems very
strange and therefore suspicious to me) you would have to do something
more like included example. But as I said I have little understanding
why the hexadecimal interpretation of the binary values should
correspond to the decimal value you want to have!
Also as you can see there is not really clear where the 00 character
belongs to. The two methods where it is either part of the multiplier or
the exponent both produce the same result for this particular example.
Which one is right if any, should be tested.
Rolf Kalbermatter
> I am reading hexadecimal format from the output of the VISA read block
> and I want to convert it to the decimal preferably exponential format.
> Example of what I read is 76 00 02 (in dec: 7.600 E+2).
> I know there is "type cast" block that converts nicelly but I am not
> sure what to specify for a type input.
> Can you show me how to apply this type cast block for in my VI so that
> it converts hex string (76 00 02) into exponential string/number
> (7.600 E+2)?
Looking at your code I see that you have not a hexadecimal string coming
back but instead a binary string. The fact that you display the string
as hexadecimal in the string indicator is just showing you the ASCII
codes of the string characters as hexadecimal numbers.
The funct
ion From Hexadecimal String expects a clear text string with
hexadecimal characters but that is something entirely different from a
binary string you choose to display as hexadecimal numbers.
An example: the binary string 7600 02 you receive from the device is in
fact the character 'v', a null character and a 02 character (or in ASCII
terms a start of text character).
So assuming your example is right (which I have to admit seems very
strange and therefore suspicious to me) you would have to do something
more like included example. But as I said I have little understanding
why the hexadecimal interpretation of the binary values should
correspond to the decimal value you want to have!
Also as you can see there is not really clear where the 00 character
belongs to. The two methods where it is either part of the multiplier or
the exponent both produce the same result for this particular example.
Which one is right if any, should be tested.
Rolf Kalbermatter
There are many ways to do this, here is a loop-free version that is relatively easy to read.
Coop wrote:
> I agree now that I am receiving the binary string at the output of the
> VISA Read.
>
> The string that I receive is in that format because the instrument
> sends it in the binary format. I did not choose to display the output
> in the binary format nor I chose to play with hex commands. The
> software version that is inside of the high voltage power supply is
> forcing me to communicate using these formats.
I know that and didn't say to try different. I also pointed out that the
example you gave me leaves much room for interpretation and I offered
you a VI diagram as attachment to convert the binary string into the
desired number in two different ways. They produce both the same result
for this particular example but are NOT e
quivalent.
Which one is right, if any, will have to be determined by further tests
and/or more detailed information from the manual. This example will at
least show you a way how you can start to work yourself on eventually
getting it right.
Rolf Kalbermatter
> I agree now that I am receiving the binary string at the output of the
> VISA Read.
>
> The string that I receive is in that format because the instrument
> sends it in the binary format. I did not choose to display the output
> in the binary format nor I chose to play with hex commands. The
> software version that is inside of the high voltage power supply is
> forcing me to communicate using these formats.
I know that and didn't say to try different. I also pointed out that the
example you gave me leaves much room for interpretation and I offered
you a VI diagram as attachment to convert the binary string into the
desired number in two different ways. They produce both the same result
for this particular example but are NOT e
quivalent.
Which one is right, if any, will have to be determined by further tests
and/or more detailed information from the manual. This example will at
least show you a way how you can start to work yourself on eventually
getting it right.
Rolf Kalbermatter
For a final solution, you should also add some error handling. For example, if the input contains illegal (non decimal) characters (e.g. 11 11 F0, 12 A2 02, etc. ) the result should be NaN.
One easy way would be to check the sum of the offsets. If it is not 6, it encountered a non-decimal character somewhere. See attached image. (The default case, just contains a NaN diagram constant wired to the output).
One easy way would be to check the sum of the offsets. If it is not 6, it encountered a non-decimal character somewhere. See attached image. (The default case, just contains a NaN diagram constant wired to the output).
