Clarify behaviour of reversion timers

[FW22]

Hi @bobfox ,

in #213 you stated, that the Ena-Register of e.g. model 704 has an impact on the reversion timer.
Chapter 3.2 of SunSpec DER Information Model Specification (issued 2021-04-22) references an Ena-register in a figure and a paragraph:

Is this the Ena register of the function (e.g. WMaxLimPctEna) or of the reversion timer (e.g. WMaxLimPctEnaRvrt)?
What is meant with "if a function setting is changed, ..."? Model 704 contains several reversion timers, this should be clarified.

We would love to see a simplification here: reset the reversion timer only, if the associated setpoint is written.

Best regards
Ferdinand

[bobfox]

The Ena reference is for the function. If there is a reversion timer set for a function and the function is not enabled, the reversion timer has no effect because the function is disabled. If the function is enabled with the reversion timer set, the reversion timer becomes active. Not enabling and resetting the reversion timer on function enable when a reversion time has been specified does not seem correct. Each of functions in the model operate independently based on their functionality. Each of the reversion timers is applicable to its respective function.

[FW22]

If the Ena reference in figure 1 is for the function (WMaxLimPctEna), could you please help me understand why a separate register is required to enable the reversion timer (WMaxLimPctEnaRvrt)?

[bobfox]

The enable associated with each of the reversion timers is the value for the function enable on reversion. For the immediate control functions in this model both the function enable and the setpoint are updated on reversion expiration. For example, if the reversion timer is active for WMaxLimPct and it expires, the value in WMaxLimPctEnaRvrt should be applied to WMaxLimPctEna and the value in WMaxLimPctRvrt should be applied to WMaxLimPct.

[bobfox]

The wording of the description of the enables associated with reversion for this model in the DER information model specification is not clear. We will update it to be more clear.

[trimble]

Is this update/clarification still in progress?