1440   Time synch for client

Created: 22 Sep 2015

Status: In Force (green)

Part: Part 8-1 (2011; Edition 2)

Links: #820 Mandatory ACSI services

Page:

Clause: Table 107

Paragraph:

Category: Issue for edition 2 of this part

Issue

It's not clear if an MMS client shall support time synch or not. Is it Mandatory, Optional or Conditional? TISSUE #820 (annex) states time synch is optional for MMS clients. Table 107 states time synch shall be implemented together with at least one other application profile. During the UCAiug Telco it was proposed to change it to conditional: "in case the client supports Operate". But is it mandatory that the Operate request shall contain a valid timestamp? People can think of an application that will check the timestamp & timestamp quality of the Operate request. Other applications don't care. So it seems be "application dependent" just like for example to use GOOSE or not for certain applications and end-users need to specify it in their specification that the MMS client shall support time synch when needed.

Proposal

Confirm that time synch for MMS clients is optional or clarify it's conditional with the condition.

Discussion Created Status
16 Dec 15 In Force (green)
Proposal in Ed2.1
For Ed2. O decided by Tissue 820 remains the standardized behavior. 		16 Oct 15 Ballot Period
Time synchronization for a Client shall only be mandatory if the client declares support for TimeActivatedControl or Logging. If one of these declarations is made, then SNTP shall be allowed as a client synchronization methodology in addition to any other methods specified by IEC 61850 (e.g. 1588). 16 Oct 15 Ballot Period
The time sync should be mandatory, this lowers the complexity and refrains from introducing an option. All users can trust that the commands can be correctly time-stamped even if they do not use the timestamp. 12 Oct 15 Discussion (red)
It can happen that a server device checks the T of on Oper command if it is valid and next to his time. So it is sometimes necessary that a client is synchronized to the time source (e.g. SNTP) also used by the servers. Or if the client also supports GOOSE.
But there are also other clients not supporting control or GOOSE, or just simulation equipment not necessarly needs a time synchronization.
It depends ... so I suggest to make it conditional, not optional. 		22 Sep 15 Discussion (red)

 

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