SupSubscripton and MaxGo / MaxSv is used to indicate how many supervision LNs can be instantiated. It is stated that: If the actually instantiated number of any category is less, the system configurator is allowed to add more as needed up to the appropriate max.
But what happens, if the number of instantiated is already more? E.g., an icd file declares maxGo = 1 but has predefined already 2. Is that valid? As specified in the standard, that does not seem to be forbidden. But allowing that, no validation can be made, if a SCT violated the rule - as in the scd file, we do not know, if the additional LGOS/LSVS were already preconfigured or not.
Propose to add a restriction that - when preconfigured LGOS/LSVS are present and SupSubscription is present, maxGo/maxSv shall not be less than the preconfigured LGOS/LSVS
16 Dec 22
One instance need to remain so that the SCT knows in which Logical Device further instances need to be located. According to published PArt 6 Ed2.1 @ definition of SupScription "and be in the same logical device."
The use case "For example an aggregation of all LGOS/LSVS statuses into a single derived LGOS/LSVS that reflects tbe state of ALL GOOSE/SV subscriptions. " is not allowed. An LGOS / LSVS cannot be used as an aggregation. The xxCBRef DO are mandatory and need to be set to indicate which subscription is supervized.
Aggregation can be made with CALH, or GAPC as a logic.
The agreegation use case is not an issue of part 6.
07 Dec 22
I don't understand the need to keep at least one instance? The SCT/ICT can always add instances of LGOS/LSVS in the future when needed.
There is also the use case of having "derived" LGOS/LSVS. For example an aggregation of all LGOS/LSVS statuses into a single derived LGOS/LSVS that reflects tbe state of ALL GOOSE/SV subscriptions. For example, MaxGO=5, and IED is using all 5 subscriptions and LGOS instances, but also want a 6th instance of LGOS that can be used to show the state of ALL GOOSE subscriptions.
05 Dec 22
agree to add following restriction to SupSubscription element description:
If maxGo/maxSv are specified >0, the total number of LGOS/LSVS shall not exceed this maximum, in any step of the engineering. The system configurator is then allowed to add and remove LGOS/LSVS respectful to this maximum and keep at least one instance, even when no subscription exists, to allow future engineering of new subscription.