Softron SerialCommander ST-3A012 is a single USB interface to four independent RS422 ports, communication unit. It is a small form factor box that you connect in USB to your Mac and it will add 4 RS422 serial ports on your Mac. The main use for that is to control multiple VTRs on one Mac, in order to record from them using MovieRecorder. If you own an M|80 for example, with 2 SerialCommanders, you can control 8 VTRs on one Mac. This is ideal if you have a large library of tapes that you want to digitise. You will be able to capture from 8 VTRs at once, using just one Mac.

Features
4 x serial RS422 ports on DB 9
No drivers required
Just connect the box to your Mac in USB
Compatible with MovieRecorder, or any other software that can use Serial RS422 ports

System requirements
separate DB9-PE connector for each RS422 port
level shifters plus Power/TXD/RXD LEDs to provide a visual indication of data traffic
powered from the host USB
maximum RS422-level data rate is 10Mbps