RE: asyn reading to waveform records

[Mark Rivers <rivers@cars.uchicago.edu>]

I agree with Eric.  The GPIB driver implements the asynOctet interface, but not the asynInt16Array, etc.  So it only knows how to read a stream of bytes, not how to assemble them into other data types.

It does seem like Dirk was identifying and fixing the problems that were preventing StreamDevice from working for your device, so that is probably the route I would suggest following.  Or else you could use one of the existing Tektronix support packages.

Mark


-----Original Message-----
From: Eric Norum [mailto:eric@norum.ca] 
Sent: Wednesday, February 01, 2012 5:53 PM
To: Rod Nussbaumer
Cc: Mark Rivers; epics Techtalk
Subject: Re: asyn reading to waveform records

This might be possible, but asynOctet is not really intended to handle multi-byte values.
Trying to coerce it to do so is likely to open several wormy cans of things like endian issues and such.


On Feb 1, 2012, at 3:44 PM, Rod Nussbaumer wrote:

> Thanks, Mark & Eric. If need be, I will take that approach, although I'm really hoping I don't have to.
> 
> Is there something I've done wrong in trying to use the waveform record in the way I've done it? It feels like I'm so close, and everything I see in the documentation and in the dbd file suggests it should be possible.
> 
>   --  rod.
> 
> Mark Rivers wrote:
>> I believe that Zen Szalata from SLAC has also recently written Tektronix scope support based on asynPortDriver.
>> 
>> Mark
>> 
>> 
>> -----Original Message-----
>> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Rod Nussbaumer
>> Sent: Wednesday, February 01, 2012 1:18 PM
>> To: epics Techtalk
>> Subject: asyn reading to waveform records
>> 
>> Hi All.
>> 
>> As a fallback alternative to my earlier problem reading oscilloscope
>> waveforms with StreamDevice (and to potentially reveal something about
>> the original problem), I am trying to use asyn to read the waveform into
>> a waveform record directly (without the aid of StreamDevice).
>> 
>> If I use the waveform record with FTVL=UCHAR or FTVL=CHAR, and
>> DTYP=asynOctetRead, I am able to acquire the scope binary-formatted data
>> into the waveform record, and I seem to be able to get the performance
>> that I require. However, this method gives me byte oriented data, and
>> the 'scope is sending 16-bit signed data. So, I tried using the
>> FTVL=SHORT, or FTVL=USHORT and DTYP set to any of the
>> 'asynIntXXArrayWfIn' data types. This results in iocInit reporting :
>> 
>>> devAsynInt16Array::initCommon, TEST:SCOPE1:CURVE find asynInt16Array interface failed
>> 
>> Some combinations of FTVL&  DTYP fail with messages like:
>> 
>>> devAsynInt8Array::initCommon, TEST:SCOPE1:CURVE field type must be SIGNED_TYPE or UNSIGNED_TYPE
>> 
>> My application dbd file contains:
>> 
>>> device(waveform,INST_IO,asynWfOctetCmdResponse,"asynOctetCmdResponse")
>>> device(waveform,INST_IO,asynWfOctetWriteRead,"asynOctetWriteRead")
>>> device(waveform,INST_IO,asynWfOctetRead,"asynOctetRead")
>>> device(waveform,INST_IO,asynWfOctetWrite,"asynOctetWrite")
>>> device(waveform,INST_IO,asynInt8ArrayWfIn,"asynInt8ArrayIn")
>>> device(waveform,INST_IO,asynInt8ArrayWfOut,"asynInt8ArrayOut")
>>> device(waveform,INST_IO,asynInt16ArrayWfIn,"asynInt16ArrayIn")
>>> device(waveform,INST_IO,asynInt16ArrayWfOut,"asynInt16ArrayOut")
>>> device(waveform,INST_IO,asynInt32ArrayWfIn,"asynInt32ArrayIn")
>>> device(waveform,INST_IO,asynInt32ArrayWfOut,"asynInt32ArrayOut")
>>> device(waveform,INST_IO,asynFloat32ArrayWfIn,"asynFloat32ArrayIn")
>>> device(waveform,INST_IO,asynFloat32ArrayWfOut,"asynFloat32ArrayOut")
>>> device(waveform,INST_IO,asynFloat64ArrayWfIn,"asynFloat64ArrayIn")
>>> device(waveform,INST_IO,asynFloat64ArrayWfOut,"asynFloat64ArrayOut")
>> 
>> 
>> As yet another possible fallback, is there a way to coerce the
>> byte-oriented data that I acquire to be 16-bit word data, perhaps using
>> a subarray record in some obscure way? I probably do need to use a
>> subarray record anyway, as there is a 6-byte header on the waveform,
>> which I need to drop.
>> 
>> For the record, this is EPICS 3.14.11 and Asyn R4-13 on x86 Linux.
>> 
>> Thanks.
>> 
>> Rod Nussbaumer
>> ISAC Controls, TRIUMF
>> Vancouver, Canada.
>> 
>> 
>> 
> 

-- 
Eric Norum
eric@norum.ca