axs527 wrote:1st: Is this possible?
It certainly should be. From your description, it sounds like a "making the Arduino speak the right language" problem.
axs527 wrote:2nd: Would I be reinventing the wheel?
If you can find another Arduino-based RS-232 controller for your specific centrifuge online, yes. I doubt that's the case, though.
Personally, I bundle "don't reinvent the wheel" in with all the grammar and composition rules they teach in high school.. rules of thumb that are handy 90% of the time, but don't stand up to scrutiny very well. I treat them more as default values than rules: if you can't articulate a reason for doing something else, follow them. If you can articulate a reason for doing something else, do whatever you want.
axs527 wrote:3rd: If it can be done, can someone without expertise in digital electronics handle this?
Barring unforeseen hardware issues you didn't mention, yes.
Communication protocols provide something called 'abstraction barriers' in hardware design. If my circuit needs to interact with a circuit directly -- I'm running wires into the chassis and creating signals within that device -- I have to know a lot about the circut I'm planning to fiddle with. If I use a communication protocol like 5v I2C, everything I need to know about that device is contained in the 5v I2C spec. I don't have to worry about talking to the other device any more, I just have to worry about talking to the I2C bus.
In this case, you just need to talk to the RS-232 bus, and the shield will handle all the voltage-and-connection stuff for you. If the shield comes with a code library, that will contain most of the "getting the Arduino to talk to the RS-232 bus" stuff. Your job will be to work at a signals-and-meanings level, which should be high-level code.
When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.