Re: stream protocol question: ASCII hex to 32-bit float

[Florian Feldbauer <florian@ep1.ruhr-uni-bochum.de>]

Hey Kevin,

I had the same problem once with a HV power supply.
I solved the problem this way:

- Read the value via StreamDevice into a longin record
- Use a sub-record to convert 32bit-int to 32bit-float

The subroutine is quiet easy:

union ficonv{
  float float_val;
  unsigned int  int_val;
};

static long intToFloat(subRecord *prec) {
  union ficonv myconf;
myconf.int_val = prec->a;
prec->b = myconf.float_val;
return 0;
}

I hope this helps!

Cheers
Florian

On 03/10/2016 05:28 PM, Kevin Peterson wrote:
> I have a helium sensor that responds to a query with this reply:
>
>    :80gv<VVVVVVVV><FFFFFFFF><CCCC><cr>
>
> Where the non-constant parts of the response are ASCII hex characters
> representing the following values:
>
>    <VVVVVVVV> = (32 bit floating point) The current gas value
>    <FFFFFFFF> = (32 bit unsigned integer) The sensor status
>    <CCCC> = (16 bit unsigned integer) The message checksum
>
> Is there a straightforward way to parse the floating point value using
> StreamDevice format converters?
>
> The raw double converter %R doesn't work, presumably because it is
> interpreting the ASCII chars as bytes, rather than hex values.
>
> The value can be read as an int with %08X, but it isn't obvious how to
> then cast that value as a float.
>
> Thanks,
>
> Kevin

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| Dr. Florian Feldbauer                |
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