In accordance with Ed.2.0 Tissue #1377, Ed.2.1 states on 'Check':
In case that the addressed function respective data object does not support these checks, the appropriate check bits shall be ignored and the command be handled.
The statement "does not support these checks" requires refinement.
The statement rules how to behave in the case of a non-alignment between a control command asking for checking and a device not supporting the check. The defined behaviour is very valid in the case of not matching configuration or misssing device capability. A control command would never be executed.
This Tissue is to ask for a confirmation that the statement is to be understood as mentioned, and not:
If a function is configured in an IED, matching with the check bit configuration in the client, but for a root cause out of the process the function does not support the check (example: VT fuse blown - no synchrocheck possible).
In such cases a control command should be rejected.
Propose to change the statement "does not support these checks" to
"does not support these checks due to missing device capability or configuration"
Extend the description of Check in Table 110 as follow:
In case that the addressed function respective data object does support these check bits but for an operational reason those checks can not be performed at the time of the request, then the performTest state fails and a negative response is sent.
If the synchrocheck is temporarily not available but check.synchrocheck = true, then the appropriate addCause is blocked-by-synchrocheck in case the performTest fails on this raising condition. Another addCause can however be returned (for instance Blocked-by-process) in case the performTest state detects an abnormal condition before involving the synchrocheck availability.