There are inconsistent requirements for setting the default value of SV APPID between 9-2LE and IEC 61869-9.
9-2LE states: "The APPID shall always be 0x4000.
IEC 61869-9 states: "The value 0x4000 is the default value, indicating lack of configuration. It is strongly recommended to have unique, source orientated SV APPID within a system, in order to enable a filter on the link layer. The configuration of APPID should be enforced by the configuration system."
APPID has opposite meanings between 9-2LE and IEC 61869-9. We need clarification within IEC 61869-9 on the following:
1. Use of APPID for preferred variants that may/may not use 0x4000
2. Use of APPID for alternative variants that must use 0x4000.
3. Configuration of the APPID should be done via ICT/SCT
It may be easiest to remove the wording that refers to 0x4000 meaning "the lack of configuration", however, this may create backwards compatibility challenges? Ideally, it should be aligned with GOOSE messages that state in IEC 61850-8-1 Ed2.1: "If no APPID is configured, the default value shall be 0x0000. The default value is reserved to indicate lack of configuration."
Note: IEC 61869-9 has reached its maturity date as of 2020. Please provide an update on the next anticipated edition/amendment.
11 Oct 22
Based on Roman's conclusion, there is no need for a tissue.
APPID can be configured to match the required value.
A reformulation/clarification related to backward mode can be proposed as a NC comment during the next circulation of the 61869-9 document.
25 Mar 22
Approval (Future Improvement)
I also agree with Roman, in particular with his statement that this is not normative (no "shall") and just a recommendation.
Recommendations (even if attributed "strongly") sometimes cause more confusion than they deliver benefits. In this sense, I suggest to rather reduce the dependencies instead of adding further definitions that interconnect things even tighter.
16 Dec 20
I do not agree with this Tissue on IEC 61869-9 for several reasons:
1) The statement in IEC 61869-9 (table 908) is *not* worded as a requirement (there is no "shall").
2) IEC 61869-9 is a profile of IEC 61850-9-2 Ed2 (normative reference).
3) Both IEC 61850-9-2 Ed2 and Ed2.1 have the following requirement (clause 126.96.36.199.2 APPID):
"The reserved value range for sampled values is 0x4000 to 0x7FFF. If no APPID is configured, the default value shall be 0x4000. The default value is reserved to indicate lack of configuration."
This default value 0x4000 indeed is taking care for backwards compatibility with 9-2LE, which does not allow to change APPID (not configurable!)
Note: The WG 10 Task Force on IEC 61869-9 alignment is asking "to no longer require support for limitations imposed by 9-2LE" (Ed1 !) in the next edition of IEC 61869-9.