The Mystery of the Clock that didn't like Summer Time

Discussion in 'C-Bus Wired Hardware' started by CABrouwes, Mar 18, 2013.

  1. CABrouwes

    CABrouwes

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    The US switched to summer time a week ago. I was expecting the Mark panel to change the clock time on my system since the daylight saving schedule is programmed. It did not happen. I then set the time one hour ahead manually on the panel and at first everything looked fine ... but at some point the system clock moved back by one hour. I also have a Wiser on the same system, so I tried setting the Wiser one hour ahead, the time changed but reversed back later. I then tried by synchronizing the time through a Piced upload. The clock on the Mark, the Wiser and every DLT seemed fine ... but a few hours later I noticed everything had reverted to winter time. (I don't know how long it takes before switching back ). By the way wiser is enable to use NTP and also has t switch to daylight saving time.

    Apparently something else on my system is opposing my efforts ! The other components that allow time setting that I have installed are thermostats.

    Can anyone explain to me what might be going one ?
     
    Last edited by a moderator: Mar 18, 2013
    CABrouwes, Mar 18, 2013
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  2. CABrouwes

    ashleigh Moderator

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    Its almost certainly the wiser.

    When a wiser is installed and set to use NTP, it is the highest priority time master.

    Note that NTP does not give you summer / winter / local time.

    NTP gives you GMT (also known as UCT), which is the world time reference. EVerything from there is a local offset. When you set a time zone on a computer you are setting the offset from GMT.

    The change from summer to winter time (and vice versa) is normally done by leaving the time zone alone, and setting a schedule to say when summer and winter time start (or to be pedantic, where summer time starts and ends). This then adds a further hour (or not) to the time zone offset from GMT. In the case of C-Bus everything is transmitted around the bus in LOCAL TIME with an indication to tell if the daylight saving time offset has been applied or not. The wiser does the translation from GMT (UCT) to local time via the time zone, and via some additional rules about when daylight saving (summer) time starts and ends.

    Suggest you check the setup of the wiser in PICED (not the wiser web interface). The start / ends in there are probably wrong.

    ---

    Now before you say: "but this is crazy why can't you idiots sort this out", the fundamental issue with summer time / daylight saving time is that it is a creation of government. And governments pass legislation in different parts of the world to change the start and end times. Sometimes for no reason, sometimes because it seemed a good idea, sometimes because they move a start or end time by a week to fit around a national holiday, etc etc.

    There's no universal worldwide maintained up-to-date database of daylight saving time start and end (bear in mind, some parts of the world have 3 timezone steps: crazy things like normal time, summer time and winter time (sigh). And the offsets are normally 1 hour but can be 2 hours in some places, and 1/2 hour in others. [Not to mention time zone offsets from GMT are normally in 1 hour increments, apart from the places that are 1/2 hour, and last I checked there is somewhere with a 15 minute increment of offset from GMT.]

    So making a piece of s/w to "just get it right" requires reading the minds of your local politicians. If yours are anything like mine, a human can't read their minds (not much to read, being mainly concrete). But if a human can't do it, a piece of s/w will never be able to.
     
    Last edited by a moderator: Mar 19, 2013
    ashleigh, Mar 18, 2013
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  3. CABrouwes

    CABrouwes

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    Thanks for your response. I checked the Wiser and it is properly set up (see attached file). The Mark is similarly set up. The problem must be somewhere else !
     

    Attached Files:

    CABrouwes, Mar 20, 2013
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  4. CABrouwes

    ashleigh Moderator

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    What is the Mark Panel ?

    Is this a security system?

    Does it also transmit date and time?

    If you have a spare PCI, you can attach this and use the diagnostic software to see where time updates are coming from. Once you know the source unit address you know which device is transmitting.
     
    ashleigh, Mar 20, 2013
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  5. CABrouwes

    CABrouwes

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    By the Mark Panel, I mean the MARK II Clipsal touch screen.
    Thanks for the suggestion to monitor the bus. I will try.
     
    CABrouwes, Mar 20, 2013
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  6. CABrouwes

    MHeaton

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    Ashleigh,
    I thought on the Summer Time issues - a large software company in Redmond issues patches the whole time to deal with this. Given that you are using NTP and hence most, if not all Wisers will have access to the internet why not host a timezone database somewhere on the clipsal web site that can expose a web service based on location or city and return the dates. That way the problem should be maintainable once for all your customers.....

    Just a thought

    Mark
     
    MHeaton, Mar 20, 2013
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  7. CABrouwes

    CABrouwes

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    The culprit was ...

    The suggestion to monitor the bus was very good. I have identified the culprit. It was a programmable thermostat that was set to provide time updates. So every two hours, it was changing the time on the bus. I disabled the function and all is fine now ! Thanks for your help
     
    CABrouwes, Mar 20, 2013
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  8. CABrouwes

    ashleigh Moderator

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    Yeah. They are issued as patches to Windows OS.

    Not in a form that is directly usable, and not something where you can inspect a patch (auto update) and see "oh gee I need to update my database".

    Certainly what you suggest is feasible in some circumstances, but sadly not all.

    Nevertheless, perhaps a Clipsal product manager will see this suggestion and look further into the viability.
     
    ashleigh, Mar 20, 2013
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