Matlab and RS232 problems

Hi, first of all, I am new into this forum, I am young, and I am french, so hello everyone, and sorry for my bad english.

Okay, I explain my problem now, I would like to receive data in live into matlab, from a wiresensor (potentiometer), through a PowerLab (data acquisition board : http://www.adinstruments.com/products
Apparently, I can give in live to matlab the voltage output of the sensor (by an extension of their software "LabChart") : http://www.adinstruments.com/products/software/labchart-extensions
And again, apparently I can process it in live in matlab : http://forum.adinstruments.com/viewtopic.php?f=7&t=390
Now what I really want, is to do some mathematical verification on my sensor signal, for example I want the value of it output voltage to be in a certain range, so matlab has to receive the signal, verify the range, and, it's my biggest problem, if it's out of range, I want matlab to send to a RS232 board a signal (this RS232 command a motor) wich will allow the sensor to go back in range).
And I don't know how to do so : I have read those articles

http://hades.mech.northwestern.edu/index.php/Serial_communication_with_Matlab
http://www.mathworks.fr/products/instrument/supported/serial.html

So do you think this is possible ? Have you ever heard or read something like that ?

Again sorry for my bad english, and thank you for futur any helps

Stanislas