Processing speeds - Limitations

Discussion in 'C-Touch/HomeGate/SchedulePlus/PICED Software' started by Roosta, Dec 9, 2014.

  1. Roosta

    Roosta

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    Hi Guys,

    Couple of quick questions for the gurus..

    What are the maximum speeds and messages CBUS is capable of processing, IE, 10 commands per 200ms? Does it vary depending on the number of units on the network, the message, ie go to level or on/off? Any way of speeding it up?

    Has the CTC got the ability to process commands faster than a Spectrum, particularly processing Serial RS232 Strings into Logic and sending out on to CBUS?

    Could the CTC process strings via Ethernet much faster than it can via the RS232 into Logic and sending out on to CBUS?

    Is there any way of getting the logic engine to read in strings longer than 8 bits?

    Many Thanks :-D
     
    Roosta, Dec 9, 2014
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  2. Roosta

    daniel C-Busser Moderator

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    The standard figure we use is 10 C-Bus messages per second. It is not affected by the number of units or type of messages. If you don't bridge between the networks you can of course multiplex multiple networks with C-Gate and have a much higher aggregated throughput, however each individual C-Bus network needs to observe that limit.

    As far as I know the CTC and Spectrum are both bound by the same internal gateway which is separate from the CPU that processes the Logic.
     
    daniel, Dec 9, 2014
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  3. Roosta

    Roosta

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    Thanks Daniel, by the sounds of that there is no advantage to me to use a CTC in this application then as the spectrum is performing flawlessly except its CBUS transmission speed..

    FYI, I am sending 5 cbus commands (2 dimmer levels and 3 on/off) per 250ms, which is 20 commands per second and it seems to keep up ok..

    Might have to look at a different control system next year.. Or alternatively look at using multiple touchscreens.. Hehehe..

    Edit: could 2 touchscreens work? Ie 5 commands sent from each per rs232 string.. Or is the speed limitation most likely the cbus network itself?
     
    Last edited by a moderator: Dec 10, 2014
    Roosta, Dec 10, 2014
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  4. Roosta

    ashleigh Moderator

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    The underlying bus is capable of approx 4500 bits / sec. These are transmitted as 9 bits (includes parity) and there are some other timing related control bits as well. Effectively you have about 400 - 420 bytes / sec as a max possible throughput.

    Then you need to add the packet header bytes, checksum, and payload. Assume typical lighting control commands use around 10 bytes on the line, and you end up with very roughly 40 commands / sec.

    HOWEVER there are also MMIs in there which consume bandwidth (dropping your average to around 30 commands / sec), and then the nature of the interface beast which also causes a drop back to around 20 commands / sec.

    So what you are seeing is about as should be expected.

    If you used a 2nd spectrum you might squeeze a little more throughput through, but not much.

    Spectrum has *loads* of horsepower.

    In general though, if you are doing anything at all that requires a long-term thrashing through of a large number of commands, then you are doing something wrong. C-Bus and all its messages / commands are designed around a general idea that messaging should be minimal.

    So if you are doing something that relies on a sustained long term deluge of messages, the general approach to take is to try and thing of some other way of achieving that outcome.
     
    ashleigh, Dec 11, 2014
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  5. Roosta

    Roosta

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    Thanks for the detailed answer Ashleigh, apologies I had missed it until now..

    My reference to a second spectrum was just a thought, however upon reflection I worked out building a second network for the 2nd touchscreen to run on would be the better way to go..

    Yes I 100% agree with your final comments and while cbus certainly was not designed for what i am tinkering with it on this occasion, it certainly has been an entertaining experiment which has achieved an end result I was hoping for (music controlled christmas light display) and considering all the equipment was from the spares/suspected faulty cupboard, the cost has been minimal..

    This has indeed sparked my interest in digging into a more specialised setup for next year..
     
    Roosta, Dec 19, 2014
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