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<== Date ==> <== Thread ==>

Subject: Re: Normative types (again...)
From: Ralph Lange <[email protected]>
To: EPICS Core Talk <[email protected]>
Date: Fri, 13 Apr 2018 21:45:36 +0200
Here's - for reference - what OPC UA defines. Pretty close to CA. Using precision on time values is interesting and makes sense.

ValuePrecision can be used for the following DataTypes:
For Float and Double values it specifies the number of digits after the decimal place.
For DateTime values it indicates the minimum time difference in nanoseconds. For example, a ValuePrecision of 20 000 000 defines a precision of 20 ms.

The ValuePrecision Property is an approximation that is intended to provide guidance to a Client. A Server is expected to silently round any value with more precision that it supports. This implies that a Client may encounter cases where the value read back from a Server differs from the value that it wrote to the Server. This difference shall be no more than the difference suggested by this Property.


On Fri, Apr 13, 2018 at 6:15 PM, Andrew Johnson <[email protected]> wrote:
Hello Kay,

On 04/13/2018 10:57 AM, Kasemir, Kay wrote:
> From: Michael Davidsaver <[email protected]>
>> ..  QSRV .. couldn't quite bring myself to publish printf-like specifiers over the network.
> I understand.
>
>> QSRV ..  Use  var("qsrvDisableFormat", "0") to enable display.format
> OK, Timo, try that.
>
> Is this a topic for the upcoming developer's meeting at BNL?

I just added it to our collection of topics to discuss then (a Google
doc linked from Tuesday's Core meeting minutes).

> The idea behind sending the printf format is that the client doesn't need to do anything but call printf.
> That doesn't work for clients which may want to use "precision from PV", but not the whole format.
>    display.precision = number of digits
>    display.type = decimal, exponential, engineering, hexadecimal, ..
> would allow sending the format hints, but then allow each client to decide which of those hints it uses.

Thanks,

- Andrew

--
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon


References:
Normative types (again...) Timo Korhonen
Re: Normative types (again...) Kasemir, Kay
Re: Normative types (again...) Michael Davidsaver
Re: Normative types (again...) Kasemir, Kay
Re: Normative types (again...) Andrew Johnson

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