850   Report Value needs a corresponding index when data-reference is set to FALSE

Created: 06 Jun 2012

Status: In Force (green)

Part: Part 7-2 (2010; Edition 2)

Links:

Page: 104

Clause: 17.2.3.2.2.1 ReportFormat Syntax

Paragraph: 1

Category: Issue for edition 2 of this part

Issue

A report only contains values for members of a dataset that have changed (as per the example associated with "Figure 32 – Data set members and reporting"). As a result of this, a report entry must indicate which member the value is for. If the DataRef is not included than this is not possible. In practise, the MMS report includes a bit string indicating which member/s in the list have been updated. This bit-string can be used to work out the index into the dataset list of each data reference that was included.

Proposal

Table 38 – Report format specification in 17.2.3.2.2.1 ReportFormat Syntax, should indicate that a MemberIndex will be included in the place of a DataRef if the option field 'data-reference' is set to false.

Discussion Created Status
09 Aug 12 In Force (green)
I suggest that we are a little bit more specific: add at the end the note: e.g., by assiging a ínclusion bitstring as defined in IEC 61850-8-1:

" ... the SCSM shall provide another SCSM specific method to relate the sent value(s) to the data set member definition(s), e.g., by assiging a ínclusion bitstring as defined in IEC 61850-8-1." 		25 Jun 12 Ballot Period
Proposed changed
add a note to data-reference in OptFlds:
An SCSM may require that the option data-reference in OptFlds shall always be TRUE. If the SCSM supports that the option data-reference can be set to FALSE, the SCSM shall provide another SCSM specific method to relate the sent value(s) to the data set member definition(s)
25 Jun 12 Ballot Period
I think I would agree to the remark of Ben. There is indeed some hidden assumption that it might be worth to spend some clarifying text in the ACSI specification. We could add some text like the following to the description of the option data-reference in OptFlds:
An SCSM may require that the option data-reference in OptFlds shall always be TRUE. If the SCSM supports that the option data-reference can be set to FALSE, the SCSM shall provide another SCSM specific method to relate the sent value(s) to the data set member definition(s)
12 Jun 12 Discussion (red)
I may not have communicated my position clearly. When receiving a report it must be possible to locate each item of EntryData [1..n] in its corresponding dataset, so that the value can update the corresponding CDC. From the SCSM for MMS, this 'look up' can be achieved with either.

a) A dataRef or
b) An index into the NamedVariableList (via the inclusion-bitstring)

I am suggesting that the ACSI should mention that each EntryData item will have either a dataRef or index into the dataset list, so that the way a report is decoded can be understood without referencing the SCSM (for the sake of clarity). How the index is implemented is entirely SCSM specific. As this is how the current MMS SCSM operates, I would assume that it is entirely backwards compatible.

I may have misunderstood the intention of the ACSI, and the vagueness surrounding how one would take a collection of EntryData values and map them back to the related DataSet is intentional (and to be resolved by the SCSM). 		12 Jun 12 Discussion (red)
If the option dataRef is not used, the SCSM has to provide a method to relate the sent value(s) to the data set member definition(s), e.g. using an data set member index or an inclusion bit string as provided in 8-1 scsm mapping.
Note:
Providing another definition (such as described in the proposal) in the ACSI would lead to backward compatibility regarding to the mms mapping, SCSM that took care of providing such a relation indication. 		07 Jun 12 Discussion (red)

 

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