The current text says:
"If the ACSI request contains a functional constraint parameter, the read request Variable AccessSpecification shall specify alternateAccess. The accessSelection of the alternate access specification shall specify component. The value of the component shall be the value of the functional constraint being specified."
The second sentence uses the wrong definition. The "accessSelection" is below selectAlternateAccess [0] IMPLICIT SEQUENCE ... (which is used for recursions).
The "component" to be specified is the one under "selectAccess".
See also attached slide with examples.
Proposal
Correct the second sentence, e.g., as follows:
The "unnamed" specification of the "AlternateAccess" specification shall be chosen, the "selectAccess" of the "AlternateAccessSelection" shall be chosen, finally the "component" shall be chosen.
Discussion
Created
Status
It is obvious to use the "unnamed" AlternateAccessSelection.
The issue is one level deeper at the "AlternateAccessSelection" ::= CHOICE ... The current definition says in the second sentence that the first choice "selectAlternateAccess" [0] IMPLICIT SEQUENCE { accessSelection CHOICE { component [0] Implicit Identifier ... should be used. This is wrong.
The second choice "selectAccess" CHOICE { component [1] IMPLICIT Identifier ... must be used!
The issue is this: is the Tag that encodes the Identifier a [0] or a [1]?
I guess that the "accepted" relates to the wrong Tag (wrong CHOICE). The "in principle" relates to the "wrong" example ... The attached pdf has three examples: the blue box is about GetAllDataValues" ;-)
Will the proposed text be used as solving the problem? I guess.
17 May 12
In Force (green)
02 May 12
In Force (green)
in principle accepted. However attached example is not about the GetAllDataValues but about the GetDataValue. There is no other way than using the unnamed AlternateAccess since the GetAllDataValues is about reading the content of a Logical Node limited to a given Function Constraint, i.e. Component=FC as defined in the text of 8-1.