Dimming Levels On Cbus

Discussion in 'C-Bus Serial Protocols' started by slychiu, Jan 30, 2011.

  1. slychiu

    slychiu

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    This may be a basic question.
    When a Cbus switch dims a light via a dimmer, it sends a Ramp to Level command. When the button is released, the switch sends a Terminate Ramp command which stops the dimming. Next there is an instantaneous Ramp to Level command on the Bus. My question is that which device is responsible for sending that final level status, the switch or the dimmer?
     
    slychiu, Jan 30, 2011
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  2. slychiu

    ashleigh Moderator

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    The sequence is:

    ON Or Off Or Ramp to Level
    followed by
    Ramp to Level OR Terminate Ramp

    In all cases the switch issues the commands.

    The choice of Ramp to Level vs Terminate Ramp depends on where the level got to.

    The reason for all this is that the master "model" of where the lamp should be is kept in the initiating unit - the switch. In the event of anything getting out of sync (which should never happen, but this extra step adds a layer of additional assurance) then the final command forces everything back in sync again.
     
    ashleigh, Jan 30, 2011
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  3. slychiu

    slychiu

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    Thanks
    So it is advisable for a switch or external device acting like a switch to send a Ramp to Level command is sent instead of a terminate Ramp, otherwise a Ctouch which is monitoring the dimming level via a slider would know what the final dim level is
     
    slychiu, Feb 1, 2011
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  4. slychiu

    Newman

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    If you have the choice, I'd recommend you use Ramp to Level commands at the end of the ramp. That way all devices are perfectly in sync with regards to what the actual level is.

    Most devices internally model the ramp, i.e. internally they track where the level has got to, but using a Ramp to Level command will guarantee all devices will have precisely the same level.
     
    Newman, Feb 1, 2011
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  5. slychiu

    slychiu

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    Thanks thats clear now
     
    slychiu, Feb 2, 2011
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