Before I forget, you may find
this link to be an interesting read. I never used Peltier for heating or cooling applications. The link hits on something interesting in that they get into using an H Bridge approach with the Peltier which makes some sense to me.
How would I have done it or gone about it? For a computer based application I would have found a module
similar to this one or a module
similar to this one. The nice thing about either is they have analog input channels as well as configurable digital I/O channels. Both modules are USB and easy to connect. What that gives me is one USB line. Much like your choice but the advantage of more channels. They also allow for very easy software writing in several languages to work with them. I am not a programmer type but I do manage to stumble along with software development in simple things like VB (Visual Basic).
The modules I linked to are just an example of a home project approach, for a real industrial application I would go with a much better module with likely 16 bit data acquisition.
The nice thing about measuring temperature is you don't need a million or more samples per second. We are not doing high speed data acquisition here. Many times 10 samples per second is more than adequate.
The sensor can be the sensor of your choice. Sensors are chosen based on the application.
The trick now becomes to signal condition the output of the sensor so we get something like 0 to whatever degrees C (or F) = 0 to 5 or 10 volts (or 4 to 20 mA for that matter).
At this point in the game we have some options. Analog Devices for example makes a variety of chips to read directly from thermocouples (and other temperature sensors). They signal condition the sensor output and give us a voltage or current proportional to the temperature. Another option is the use of little Temperature Transmitters which are an off the shelf solution. Let's not leave out the use of a PIC based system either.
Once we have our signal we write the software to read and display what we have. The software also sends signals to the digital outputs of our module. That is where our control begins. I generally use large heating elements for heat.
Along these lines, several years ago I built a small temperature monitoring system for a computer hardware website to show what goes on with temperatures within a computer case. What is left of that science experiment (
) can
be found here. The code could have easily been expanded to drive a digital out on the module I used.
I seriously believe that working with temperature control is much like getting to Rome in that there are a dozen ways to go about it.
Ron