Connecting a Bronkhorst MV-306 via RS232 to the computer is a easy thing, when you don’t forget to set the rs232 signal ground to ground. All you’ve to do is connect PIN 2 (RxD Receive Data), PIN 3 (TxD Transmit Data) and PIN 5 (Signal Ground) with the Pins of the MV-306. The pinout of the MV-306 is 1 Tx-RS232, 6 Rx-RS232 and PIN 4 and 8 are ground.
Use this setup and the things works just fine:
RS232 PIN 2 <–RxD–> MV-306 PIN 4
RS232 PIN 3 <–TxD–> MV-306 PIN 1
RS232 PIN 5 <–Ground–> MV-306 PIN 4,8
This works right for me, i’m not responsable for any damage happens to you or your equipment.