Sam, I don't understand your reasoning here completely. With DALI you can have groups. More importantly you can wire up mains as one circuit because you don't need to HARDWIRE your groups. Your groups can cross mains. With 0-10v lots of hardwiring for groups of lights and when you want to change groupings you typically need to change wiring. Not so with DALI. Again, really low cost per group. So, to say some spare I/O is available on existing controllers for free is a misnomer. You in fact paid for that I/O. Anyway, you can't show up labor-wise on a project where the cost of a DALI multi-master is of any concern cost-wise.
Good day Sysint,
I think we have hijacked this thread a bit too much and so we maybe should start another to discuss this further. However, for now I will respond and also apologize to CM for the hijack!
Firstly, my previous comments are not my reasoning, but a lot of the customers I speak with... Just to clarify, this is from the perspective of a mini-retrofit and not a major one and/or a major lighting upgrade. So, saying that this is the deal:
1. Customers already have their lights banked, etc and currently have minimal need (are uninterested) to individually control each ballast.
2. A number of Customers have their banked lights wired to a single electrical room and are controlled by contactors/relays.
3. Most Customers as in (2) above are uninterested in dimming unless they take on a major lighting retro-fit and/or major upgrade... which they are holding off because of the economic climate and/or they have other priorities (i.e. other parts of the building are needing attention).
So, their responses are as follows:
A. Adding some lighting control is desirable, as this can reduce some of their operating costs... automatic turning on/off lights is a good first step.
B. Customers in scenario (1) and (2) just need to control the contactors/relays and so this can be easily done via some spare outputs on some of their HVAC controllers... thus, no need to purchase, install, recommission, and be trained on a new controller that would be needed for Dali. They recognize that they will have limited lighting control (as compared to what you could do), but they do not care and the cost/benefit scenario is hard to digest for the powers that be.
C. Some Customers in scenario (2) that want a few ballasts to be dimmable (i.e. some within parkades) recognize that re-wiring will be necessary... So, since the number of ballasts needing to be changed and re-wired for 0-10 are small, they see no magnitude difference in cabling costs between 0-10 and Dali (they are already paying a guy already and/or have their own electrical personnel... and wire itself is rather inexpensive compared to labor). Remember this is a specific case (parkades) where wiring and electrical access is not an issue. As with (B) above, they already have HVAC controllers with some spare AOs and so no need to purchase, install, recommission, and be trained on a new controller that would be needed for Dali.
D. Some customers are doing small retro-fits on office floors by using dimmable ballasts (0-10) with ambient light sensors (around $150) controlling the ballasts. They recognize that this scenario is less than optimum (no overall building control of the lights), but wanted to start somewhere. I would submit that this case would be perfect for Dali, etc but the customers did not want to go this route (or any building controller approach) and their reasons/rationale were not reflected to me.
As for your comments about spare I/O and that it is not free... Here is where we differ... The customers has already paid for the install and commissioning of an existing controller some time ago... and so any unused I/O that can be used for their lighting is effectively "free"... except for some programming change on the head-end that is relatively trivial for them, as they typically do this in house.
Anyway, I hope I have clarified myself further.
Cheers,
Sam
