Puritan Bennet 840 Serial Port connection

I'm having problems to connect PB 840 to a MacBook. I'm using a serial to USB cable. Despite I installed OpenICE and Java, the Device Adapter does not recognizes it, just shows bluetooth port of the Mac. I installed another app called "Serial" and it reads the serial port but I want realtime, high frecuency data to build waveforms and make lung mechanics analysis. What I'm doing wrong?