Experimental Physics and
Industrial Control System

Eric Norum <[email protected]> · Tue, 11 Sep 2012 08:22:49 -0700

On Sep 11, 2012, at 7:02 AM, [email protected] wrote:

> I would have thought the "%8R" stream device converter would do the job. 

I don't believe that it would.  The '%R' converter is 'too raw'.
For example, writing using %4R would send the four bytes, but wouldn't convert them to two 16-bit base-16 strings as described below.

> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Florian Feldbauer
> Sent: 11 September 2012 14:46
> To: Mark Rivers; EPICS tech talk
> Subject: Re: ISEG EHS device support on the Raspberry Pi Computer
> 
> Hi,
> 
> thanks for your replies. Writing an asyn driver seems a pretty good idea.
> 
> But for the EHS modules from ISEG, I don't think StreamDevice would be 
> feasible.
> Maybe I'm biased due to our old CAN interfaces.
> Up to now we used asynDriver and StreamDevice to control these modules. 
> But our CAN interfaces were in principal
> RS232- or USB-to-CAN converters which read/write ASCII-Strings. Every 
> single byte from the can frame was coded as 2 digit hex value
> separated by blanks (somethink like "ab 24 1f 05").
> The EHS modules use 32bit float values for currents, voltages and 
> temperatures. So we needed to convert a IEEE754 32bit float
> to something which stream could write like "%02x %02x %02x %02x", or the 
> other way around.
> 
> Therefore I think a device support for this modules would be more feasible.
> Sure, if we write our own asyn driver one could think about an interface 
> which reads/writes bitstreams, so we don't need such a conversion.
> 
> Best regards,
> Florian
> 
> 

-- 
Eric Norum
[email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System