Timers on Reef-pi

[haley-pi]

Hey Everyone,

How Does Reef Pi's timers react to power failures?

I have set my co2 up with the following timer. If I lose power before a state change, and regain it after, Will the state change be ignored?


For example, if the power turns off at 11:55, then comes back at 12:05, will the co2 be on?

Thanks

 

[mbartho]

Did you find an answer to this? I would like to know this as well.

 

[haley-pi]

Did you find an answer to this? I would like to know this as well.

Yes.

to quote Ranjib ‘...
Light, outlet state etc should sync back after power outage soon as reef-pi start or within a minute (for lights). Macro, timers that reverts back after a duration etc will lose their on-the-fly state and will be impacted (e.g, there revert after a duration part might be lost since timer trigger point is passed).’

 

[Ranjib]

Yes. Timers with simple action such as just turn on a thing at a specific time are pretty stable and should not be hampered by power cycle. But an example like the one presented here, where it turns back off after a long time can be impacted badly. As in if the timer started and then power cycles , the revert back action will be impacted , since the timer that started is gone . And it will not trigger back again till next interval. For this reasons , it’s better to split such timers into two different ones , one for on and one for off if you are worried about power cycle in between.

 

[Des Westcott]

Yes. Timers with simple action such as just turn on a thing at a specific time are pretty stable and should not be hampered by power cycle. But an example like the one presented here, where it turns back off after a long time can be impacted badly. As in if the timer started and then power cycles , the revert back action will be impacted , since the timer that started is gone . And it will not trigger back again till next interval. For this reasons , it’s better to split such timers into two different ones , one for on and one for off if you are worried about power cycle in between.

Will a real-time clock help with this @Ranjib ?

This is definitely a good argument for backup power for the Pi. Not necessarily for the equipment, but definitely to keep the pi alive so it remembers all it's states and timers / macros it has running.

 

[Ranjib]

Will a real-time clock help with this @Ranjib ?

This is definitely a good argument for backup power for the Pi. Not necessarily for the equipment, but definitely to keep the pi alive so it remembers all it's states and timers / macros it has running.

yes, it will , but only to some extent. An RTC module will make sure time does not drift once pi comes up after power outage (i.e. it will reduce the chance of timers start at wrong time or not starting at expected time ., ) . it will not solve the issue of lost state of timers that were already running during the outage.

 

[attiland]

yes, it will , but only to some extent. An RTC module will make sure time does not drift once pi comes up after power outage (i.e. it will reduce the chance of timers start at wrong time or not starting at expected time ., ) . it will not solve the issue of lost state of timers that were already running during the outage.

I don’t understand why it is not sorted a long time ago. It might be just me but I think this is a big flow of many DIY systems I have looked at. In some of my other projects I use a timer test routine which tests switch states against a timer. So if no override flags set it switches it to the state where it should be. To translate it to a reef example the pump should be on between 1-2pm. The system starts at 1:20pm so it has missed to turn on the pump at 1pm. Routine identifying it should be on and no maintenance flag so if it is off it turns it on. This is easy workaround of missed timer events. Of corse RTC is a must for such a routine to run reliably.