Hi Sekar,

When you now open your thread, you will see many useful posts - some guiding you and some guessing for you as you have kind off left many ends dangling loose !!

And before I answer you, let me tell this : AC Plant = Air Conditioning plant ! I was surprised to find that this abbreviation is not very popular. In India this is a very common usage. One more reminder to desist using abbreviations and SMS lingo when posting messages.

Coming back to your queries, I will just give some hints which you can develop ON :

1. Since you seem to be familiar with High Level Languages, migrating to MCU coding will be demanding initially. You need to rub shoulders with hardware - there is no alternative to this even if you use a language like C or Pascal. MCUs are mean machines and can execute code at track-burning speeds as they are totally focussed on the single job they are assigned and don't have the burden of the OS to lug around. You have to get used to code that fits in kB levels rather than the MB and GB levels that you are used to ! Yes this embedded world is a religion of men and women with both hardware and software exposure.

2. To handle 10 channels of analog data an 8 bit MCU is quite fine. In fact the channel count has little to do with the data width. Just to make it simple, with an input signal range of 0-10V dc, an 8 bit ADC will be able to resolve the input into 256 steps or 40mV / step roughly. And a 12 bit ADC will resolve it to 10000/2^12 steps or 2.44mV. And so it goes. Thus YOU have to decide what resolution you want and then pick up the ADC ( it does not end there - then comes the type of ADC : SAR, Integrating, Delta_Sigma...to name a few) . OK you know you need 12bit ADC - so do you look for a MCU with a data width of 12 bits ? NO. Never. you simply use a 8 bit MCU and read the ADC twice for every sample - 8 bits first and 4 bits next. Get the idea?

3. So for the time being drop the idea of 16bit MCUs and C# programming. You will have to code either in assembly language or in C ( modified for small devices like MCUs). Visit http://www.keil.com for more on this - you can even download the evaluation copy of the C-Compiler they have for trying out.

4. Instead of asking what processor to use and what data width, I would suggest that you simply post details of the AC plant controls that you want to achieve finally. Then we will very fast reach the basic blue print for the hardware.

Cheers.

Raghu