1727   There is no ExtRef equivalent to configure ORG.setTstRef

Created: 21 Oct 2020

Status: Discussion (red)

Part: Part 6 (2019; Edition 2.1)


Page: 44

Clause: 9.3.1

Paragraph: 1


As it is detailed in IEC61850-7-1 clause 7.8.3, the inputs of a function can be modeled as an "InRef" of CDC type ORG.
This CDC holds the main source of the input "setSrcRef" along with another reference used for testing "setTstRef" that can be dynamically activated.

The value within "setSrcRef" is the logical equivalent to the matching "ExtRef" which has a matching "intAddr" value.

Since there is no distinct "intAddr" for the test signal "setTstRef" within an ORG, it is currently impossible to configure it the same way we can configure the "setSrcRef" using "ExtRef".


The simple solution is quite trivial, but will impact interoperability:

Add another XML node named "TstRef" that can be added in the Inputs section along with the existing "ExtRef".

Discussion Created Status
I would assume this is not interoperability - shall we set that to future improvement? 03 Jun 21 Discussion (red)
proposal to add new InputTstRef with same content as ExtRef 22 Feb 21 Discussion (red)
Usage of ExtRef is intended to allow an SCT to not work at InRef (or BlkRef) DOs level to try to segregate role of tools. Using ExtRef to engineer setSrcRef and directly write setTstRef whithout any check as possible with ExtRef is risky for SCT.

I agree that TstRef may help in addition to ExtRef.
22 Feb 21 Accepted
It is true that it could be possible to use values supplied by the SCT in setTstRef and setTstCB to configure the test reference. But without an ExtRef equivalent, we cannot express in SCL the detailed mapping of the tstRef at the attribute level.

Using setTstRef also creates 2 different ways to configure the referenced signals: Use ExtRef for one and setTstRef for the other.

Using an equivalent to ExtRef for the test reference would also allow a device to specify a different preferred service for test references. For example, if a device prefer to use MMS for tests values.
28 Oct 20 Triage
It is currently possible to configure the setTstRef as well as the setTstCB: the SCT writes the reference both of the test signal as well as the reference of the control block that is transmitting the signal.
This means that ICT/IED that supports the InRef.tstEna are able to configure the subscription of test environment variables (GOOSE, SMV, Report) via the analysis of the DAs setTstRef and setTstCB, while the configuration of the operational subscription is performed as specified in 7-1 Normative Annex A with ExtRef.
22 Oct 20 Triage


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