topic Re: Convert Hexadecimal String to Byte Array in LabVIEW

Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 04:47:16 GMT

Hi,

I would like to convert an Hexadecimal String (e.g. 0x156FD18A4) to a Byte Array, the problem is that I do not have any delimiter (e.g 15 6F D1 8A 4) so I cannot use the Spreadsheet String To Array function, I tried to do something on my own, but everything seems to be too complicated is there any proper, clean and neat way to achieve what I want? (or maybe a smart trick to add delimiter every two characters in my original String)

Thanks!

Re: Convert Hexadecimal String to Byte Array

Vijay_J — Tue, 30 Sep 2014 05:06:18 GMT

Use the LabVIEW inbuilt function "String To Byte Array"

Re: Convert Hexadecimal String to Byte Array

altenbach — Tue, 30 Sep 2014 05:07:05 GMT

Please attach a VI containing a typical input string as a diagram constant.

In the input a hdexadecimally formatted string starting with "0x" and followed by a string if characters in the range A..F?

What is the max (or fixed) lenght of the string? Does it represent a numeric of known representation?

Re: Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 05:48:23 GMT

@Vijay_J wrote:

Use the LabVIEW inbuilt function "String To Byte Array"

Ok seems I was not clear enough, I do not want the value of the ASCII characters so this "LabVIEW inbuilt function "String To Byte Array"" cannot work unless I do some tricks substracting a certain number but to me it seems a bit weirdo to do that (but true I could do that to some extent,

A = 65 => 65 - 55 = 10, altough I don't really like the idea to rely on a blurry definition of what character set (i.e. encoding) is used through this conversion).

Here is a example of what I want to achieve:

Let's say my input is "0X465F66A54", ok I can trim the two first characters at beginnning of that Hexadecimal String and get something like that: "465F66A54".

Now I would like to convert it to the corresponding Byte Array matching the Hexadecimal Numbers represented by this Hexadecimal String aka:

46 5F 66 A5 (0 left padding)4

Here is the Bytes I want to get (0x is just here to indicate the radix)

0x46 [0]

0x5F [1]

0x66 [2]

0xA5 [3]

0x04 [4]

Is it clear enough now, or do I need to explain something else?

Oh last thing, about the string length, I don't really know but it can be pretty lon (e.g 42, 43 up to a few undreds of characters), and as it was introduced in the example above the string length is not necesserarly a multiple of two.

Thanks,

Re: Convert Hexadecimal String to Byte Array

Vijay_J — Tue, 30 Sep 2014 06:02:30 GMT

@Nelval wrote:

@Vijay_J wrote:

Use the LabVIEW inbuilt function "String To Byte Array"

Ok seems I was not clear enough, I do not want the value of the ASCII characters so this "LabVIEW inbuilt function "String To Byte Array"" cannot work unless I do some tricks substracting a certain number but to me it seems a bit weirdo to do that (but true I could do that to some extent,

A = 65 => 65 - 55 = 10, altough I don't really like the idea to rely on a blurry definition of what character set (i.e. encoding) is used through this conversion).

Here is a example of what I want to achieve:

Let's say my input is "0X465F66A54", ok I can trim the two first characters at beginnning of that Hexadecimal String and get something like that: "465F66A54".

Now I would like to convert it to the corresponding Byte Array matching the Hexadecimal Numbers represented by this Hexadecimal String aka:

46 5F 66 A5 (0 left padding)4

Here is the Bytes I want to get (0x is just here to indicate the radix)

0x46 [0]

0x5F [1]

0x66 [2]

0xA5 [3]

0x04 [4]

Is it clear enough now, or do I need to explain something else?

Oh last thing, about the string length, I don't really know but it can be pretty lon (e.g 42, 43 up to a few undreds of characters), and as it was introduced in the example above the string length is not necesserarly a multiple of two.

Thanks,

Please refer the attachment and VI snippet

Re: Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 06:09:51 GMT

@Vijay_J wrote:

@Nelval wrote:

@Vijay_J wrote:

Use the LabVIEW inbuilt function "String To Byte Array"

Ok seems I was not clear enough, I do not want the value of the ASCII characters so this "LabVIEW inbuilt function "String To Byte Array"" cannot work unless I do some tricks substracting a certain number but to me it seems a bit weirdo to do that (but true I could do that to some extent,

A = 65 => 65 - 55 = 10, altough I don't really like the idea to rely on a blurry definition of what character set (i.e. encoding) is used through this conversion).

Here is a example of what I want to achieve:

Let's say my input is "0X465F66A54", ok I can trim the two first characters at beginnning of that Hexadecimal String and get something like that: "465F66A54".

Now I would like to convert it to the corresponding Byte Array matching the Hexadecimal Numbers represented by this Hexadecimal String aka:

46 5F 66 A5 (0 left padding)4

Here is the Bytes I want to get (0x is just here to indicate the radix)

0x46 [0]

0x5F [1]

0x66 [2]

0xA5 [3]

0x04 [4]

Is it clear enough now, or do I need to explain something else?

Oh last thing, about the string length, I don't really know but it can be pretty lon (e.g 42, 43 up to a few undreds of characters), and as it was introduced in the example above the string length is not necesserarly a multiple of two.

Thanks,

Please refer the attachment and VI snippet

This does not work either: the output is a String Array (and not matter what value contained in are not really matching the representation of the bytes contained in the Hexadecimal String).

Re: Convert Hexadecimal String to Byte Array

altenbach — Tue, 30 Sep 2014 06:27:45 GMT

@Vijay_J wrote:
Please refer the attachment and VI snippet

So, why is the input string set to hex display?

If the lenght is odd, Is the right-most hex character always padded on the left with zero?

Re: Convert Hexadecimal String to Byte Array

Vijay_J — Tue, 30 Sep 2014 06:28:36 GMT

Either entire string should be treated as Hex or Normal one all along

Output byte array for the input hex string "465F66A54” is as follows

0x46 [0] - > 70

0x5F [1] - > 95

0x66 [2] - > 102

0xA5 [3] - > 165

0x04 [4] - > 4

This is what exactly the "String To Byte Array" function does. Converting the Number/decimal/Unsigned integer to hex string is performed by "Number To Hexadecimal String".

Please refer the attachment. Hope I have conveyed, if not may be I did not understand your requirement correctly.

Thanks,

Vijay.

Re: Convert Hexadecimal String to Byte Array

Vijay_J — Tue, 30 Sep 2014 06:34:49 GMT

@altenbach wrote:

@Vijay_J wrote:
Please refer the attachment and VI snippet

So, why is the input string set to hex display?

If the lenght is odd, Is the right-most hex character always padded on the left with zero?

As a sample VI, control accepting hex string directly, otherwise LabVIEW will perform the ASCI conversion.

Second, I haven't considered the length as odd or even. It always segregates from least significant bytes.

Re: Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 06:48:04 GMT

@Vijay_J wrote:

Either entire string should be treated as Hex or Normal one all along

Output byte array for the input hex string "465F66A54” is as follows

0x46 [0] - > 70

0x5F [1] - > 95

0x66 [2] - > 102

0xA5 [3] - > 165

0x04 [4] - > 4

This is what exactly the "String To Byte Array" function does. Converting the Number/decimal/Unsigned integer to hex string is performed by "Number To Hexadecimal String".

Please refer the attachment. Hope I have conveyed, if not may be I did not understand your requirement correctly.

Thanks,

Vijay.

I agree with comment made above about the hexadecimal display. When I receive the String, it is already a Hexadecimal Format why should I need to use the Hexadecimal of a String Control... that actually makes absolutely no sense at all! (especially when the value are converted to their ASCII equivalent), I though I made myself clear with my example.

But I'm struggling about how to make it even more clear now, it is quite crystal for me.

Here is attached an example but using a space delimiter as a separator in the Hexadecimal Input String, how to achieve the same with if I do not have the same separator between each Byte Representation in the orignal Hexadecimal String?

Re: Convert Hexadecimal String to Byte Array

GerdW — Tue, 30 Sep 2014 06:53:42 GMT

Hi Neival,

something like this may work for you:

(String in normal display mode…)

Re: Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 07:21:04 GMT

I already came up with a solution pretty similar, I was expecting something a bit more builtin from LabVIEW, anyway, thanks.

Re: Convert Hexadecimal String to Byte Array

Vijay_J — Tue, 30 Sep 2014 07:34:48 GMT

Sorry for the misunderstanding... another way of doing the conversion

Re: Convert Hexadecimal String to Byte Array

altenbach — Tue, 30 Sep 2014 07:36:41 GMT

And where do these "solutions" do a left padding of the last "4" in the original example string?

Re: Convert Hexadecimal String to Byte Array

GerdW — Tue, 30 Sep 2014 07:44:09 GMT

Hi Christian,

why insist on left padding? Conversion of trailing "4" will give the expected result 4…

The question should rather be: Why does the data source omit the zero padding leaving us with an odd number of chars?

Re: Convert Hexadecimal String to Byte Array

altenbach — Tue, 30 Sep 2014 07:55:23 GMT

@GerdW wrote:

why insist on left padding? Conversion of trailing "4" will give the expected result 4…

Yes, yours does, but the other two don't.

Re: Convert Hexadecimal String to Byte Array

altenbach — Tue, 30 Sep 2014 08:07:31 GMT

Here's what should cover all scenarios (odd or even lenght)

Re: Convert Hexadecimal String to Byte Array

Nelval — Tue, 30 Sep 2014 08:32:08 GMT

@altenbach wrote:

Here's what should cover all scenarios (odd or even lenght)

Thanks for completing that part of the solution.

Re: Convert Hexadecimal String to Byte Array

DavidBoyd — Tue, 30 Sep 2014 17:26:26 GMT

I know this post has been marked answered, but I just can't help myself. And I do have the greatest respect for Chris' experience.

Mostly in answer to Vijay's several attempts (some flat-out wrong, and the final one close but improvable), I'll attach the following two images (note, only one is a snippet):

Apologies to all and best regards,

Dave

Re: Convert Hexadecimal String to Byte Array

Darin.K — Tue, 30 Sep 2014 20:32:54 GMT

for the fun of it: