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Design of multichannel A/D controlled via RS232

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yiovanni

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Hi,

I am trying to design a circuit to monitor up to eight analog voltages ( 0-5V). So, I need to design an 8-channel A/D with an RS232 interface so I can monitor and control the circuit through a PC ( maybe a Visual Basic program). I am trying to implement the circuit with with the fewest possible components due to space constraints.

I would appreciate any suggestions, ideas, possible existing designs or totaly integrated solutions anything that might put me in the right path !

Thanks,

Yiovanni
 

You can find 8 cahnnel input ADC on the market
check TI for example.
It is also important what is your targetted
sampling rate and resolution
 

Check with Maxim as well, they have app notes for A/Ds parallel
and serial interfaces.

Tornado
 

A/D PCI cards or any others that you install inside your computer are pretty expecive. If you don't want to spend U$500+ forget about them.

If you don't need 10 thousand samples/sec find a data logger which uses command-response protocol and has RS-232/485 interface.
Usually as command they use short ASCII string and as retururn you receive another ASCII string which contains result of A/D conversion of interrogated channel.
You will be able to configure inputs +/-10V, 0-5V etc.. and in most cases 12bit resolution will be more than enough.
Now, you can write your program in VB, LabView .....and monitor your channels.
 

Thanks for the suggestions. I am simply looking for the fewest possible ics so I can put this circuit together. So my question is what is the solution that will allow me to use the smaller number of components. 8 -bit resolution will be fine, and data sampling frequency it is low.

Yiovanni
 

Choose uC with built-in A/D converter. (you can go to www.semiconductors.philips.com ) Eg. P87C552 - 8 -10b A/D 0-5V + UART. Next component you will need is RS-232 driver Eg. MAX202 + 4x100uF caps.

Each input you should protect with 100Ohm resistor (in series) and ZD 5.1V.

And that is it!!!
 

Ianp,

Thank you. I'll try what you suggested.

Yiovanni
 

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