Experimental Physics and
Industrial Control System

[email protected] (Bob Dalesio) · Mon, 07 Feb 2000 10:00:27 -0700

At 12:40 PM 2/7/00 +0100, Benjamin Franksen wrote:
>Leo R. Dalesio wrote:
>> 
>> I would think that a soft bo with an undefined DOL that has
>> been processed at initialization should be 0 and defined. If someone
>> wanted the value to be something other than 0 - they could have put
>> the constant 1 in the DOL field. As some of the configuration tools
>> do not define a field if it is the same value as the default, an undefined
>> field should be construed as a 0. Just my opinion....
>
>The question is, of course, relevant to output records in general.
>
>The Release Notes to R3.13 say: "Another feature is is that it is now
>possible to distinguish link constants with a value of 0 from links that
>have never been given a value".
>
>I believe that the distinction between zero ("0") and undefined ("") has
>been made in order to allow undefined links to be completely ignored by
>the record support in contrast to constant-zero links. Link behavior
>should be consistent throughout the system and IMHO undefined is not the
>same as zero.
>
>If people want to have a zero value at init, they can either set it in
>the database, or, if they insist on a different *default* behavior for
>the DOL links, we (or they) can set 'initial("0")' in the record's
>definition of the DOL field and everything works as expected without
>changing the record support.
>
>I'd like to know if it is the general opinion that an output record that
>has been processed is defined (i.e. UDF==FALSE), even when 
>- no value has been put into VAL,
>- DOL is undefined, and
>- no readback was done by the device support.
If PINI is set to Yes and the record gives it nothing to do -
that is to say:
	DOL is undefined
	Nothing has been put into VAL
	There is no device support from which to read the new value
Then the initialization is done and it should not be UDF

	Bob

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System