Re: writing your own stream cronverter

[Emmanuel Mayssat <emmanuel_mayssat@lynceantech.com>]

To answer my own question...
The type returned by parse is the type of the EPICS record.

To populate several records with the same reply, one needs to use a
trigger record (a standard ai record (devaiStream)) and other slave
records (scan set to Intr I/O scan and protocol with only "in"
directives). The "out" directive is set in the protocol of the trigger
record.

Cheers,
--
Emmanuel




On Mon, 2007-12-03 at 11:57 -0800, Emmanuel Mayssat wrote:
> Dirk, others,
> 
> I am trying to write a new converter.
> That converter is almost like the RawConvert except:
> * the bit order and meaning are the same a C float ( sign + mantissa +
> exponent )
> * the content is coded on 4 bytes
> * Width is not meaningful, big/small endian may be
> * Several values should be extracted from the same reply ( 25 ai ). So
> devaiStream does not work.
> 
> 
> I looked at the existing converter.
> A converter has 3 methods parse, print, read/scan.
> Parse returns a type (long, double, string, etc.), what is this type
> referring to? The input (4*8 bits), the value (float), other ?
> I understand that it is used to find the correct print/read methods but
> what should it be in my case? 
> 
> If Read/scan method returns the # of bytes read, I should be forced to 4
> in my case? Is the return value always the number of bytes?
> 
> I want to assign the values of several records based on the returned
> message. Should I create a custom record with 25 additional fields when
> compared to ai and then soft link them to other AI. Is there a way to
> use devaiStream and directly populate the 25 records? 
> 
> getStatus {
> out "GET STATUS"
> in  "%(record1.val)R%(record2.val)R%(record3.val)R"
> }
> 
> Thanks,
> 
> --
> Emmanuel
>