Later Binding on specific file does not work

[JakobVogelsang]

Describe the bug
The GOOSE type later binding plugin does not show any ExtRef when clicking on data

To Reproduce
Open appending file

1. Go to Subscribe - Later Binding (GOOSE)
2. Click on '´data'
3. See no reaction in possible inputs

Expected behavior
A selection of inputs or a warning that there are none

Additional context
See file
LaterBindingGOOSEError.scd.zip

[danyill]

I have the same issue for both GOOSE and SV when using Edition 2.1 with Siemens SIPROTEC 5 devices.

The attached scd may help reproduce this.

XAT_Prot2_Base_Configuration.scd_1.zip

[danyill]

@JakobVogelsang I'm a bit confused by your specific file. There is a single IED, and I would not expect there to be any possibility of subscribing to anything else. There are no ExtRefs in this file.

What did I miss?

[danyill]

I thought I might try to diagnose the issue I'm having with Edition 2.1 DIGSI 5 SCL files. It is caused by:

open-scd/src/editors/subscription/later-binding/ext-ref-later-binding-list.ts

Lines 136 to 148 in 48ef7ea

	private isSubscribedTo(extRefElement: Element): boolean {
	return (
	extRefElement.getAttribute('iedName') ===
	this.currentIedElement?.getAttribute('name') &&
	this.sameAttributeValue(extRefElement, 'ldInst') &&
	this.sameAttributeValue(extRefElement, 'prefix') &&
	this.sameAttributeValue(extRefElement, 'lnClass') &&
	this.sameAttributeValue(extRefElement, 'lnInst') &&
	this.sameAttributeValue(extRefElement, 'doName') &&
	this.sameAttributeValue(extRefElement, 'daName') &&
	this.checkEditionSpecificRequirements(extRefElement)
	);
	}

Specifically in L141: this.sameAttributeValue(extRefElement, 'prefix') && .

When we do the comparison:

the FCDA might be:

<FCDA ldInst="Application" prefix="" lnClass="LPHD" lnInst="1" doName="Sim" fc="ST" />

And the ExtRef might be something like (not an exact match):

<ExtRef desc="RxPos1" intAddr="RxPos1;/Pos/stVal" pServT="GOOSE" pDO="Pos" pDA="stVal" iedName="XAT_232_M2" ldInst="CB1" lnClass="XCBR" lnInst="1" doName="Pos" daName="stVal" serviceType="GOOSE" srcLDInst="CB1" srcLNClass="LLN0" srcCBName="Ind_0" />

Note, there is no prefix. This is optional and the default is the empty string in the standard:

What we do is:

  private sameAttributeValue(
    extRefElement: Element,
    attributeName: string
  ): boolean {
    return (
      extRefElement.getAttribute(attributeName) ===
      this.currentSelectedFcdaElement?.getAttribute(attributeName)
    );
  }

Where: extRefElement.getAttribute(attributeName) = null (there is no prefix is the extRef)
And this.currentSelectedFcdaElement?.getAttribute(attributeName) = ""

So what happens is we end up comparing null with an empty string which fails and so the subscribed ExtRef is not shown.

Do we need to compare the prefix? Is the FCDA fully qualified without it if it is an optional field?