Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 19 Nov 2013 12:53:44 -0600

Hi Mark,

The return value from an ao device support's init_record() routine

doesn't cause LINR to be changed at all, it only affects whether the

RVAL field value gets propagated back to the VAL field at startup.

However unless the device's write_ao() routine actually looks at the

LINR field, the user may set it without that having any affect on the

value that gets passed to the driver.

In most cases the unit conversion and adjustment fields do not affect

the values output or input by device support that takes or return the

value in engineering units. Device support *may* use the values in those

fields (ESLO, EOFF, ASLO, AOFF etc) if the author wants to, but I can't

think of any that actually do so. They would have to duplicate some of

the code from the record though, since its calculations only go to/from

a 32-bit integer value in RVAL, thus losing data. I could see that as

being useful for this kind of case, but documentation for the device

support should make it clear for users that it is doing this.

- Andrew

On 11/19/2013 11:57 AM, Mark Rivers wrote:

I don’t think you can do these types of conversions with the asynFloat64
device support for the ao record.  devasynFloat64.c::initAo always
returns 2, which means “do not convert”.  In aoRecord.c that means that
LINR is always left at the default value of menuConvertNO_CONVERSION.
So this means that the ao record never does any conversions with the
asynFloat64 deice support.

Mark

*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Benoit
*Sent:* Tuesday, November 19, 2013 11:16 AM
*To:* [email protected]
*Subject:* Convertion for asynFloat64

Hi,

I would like to use mV in my EPICS folder and send V to my driver.

I have done conversion correctly using asynInt32 type but it doesn't
work with asynFloat64.

Do you have any suggestion?

    record(ao, "$(S):$(D)_$(C):CavVoltSet")
    {
        field(DTYP, "asynFloat64")
        field(OUT,  "@asyn($(PORT),$(ADDR),$(TIMEOUT))cavvolt")
        field(PINI, "YES")
        field(LINR,"SLOPE")
        field(ESLO,"0.001")
        field(PREC, "2")
    }

I have try with

        field(LINR,"SLOPE")
        field(ASLO,"0.001")

and also with

             field(LINR,"LINEAR")
             field(EGUF,"1000")
             field(EGUL,"0")

But nothing seems to change when I receive my value in my asynPortDriver.

Regards,

--
Benoit RAT
www.neub.co.nr <http://www.neub.co.nr>

--
Advertising may be described as the science of arresting the human
intelligence long enough to get money from it. -- Stephen Leacock

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System