Over the years different industries have adopted different means of data transmission for different reasons. If you're going to communicate with them all, you need the right converters.
Black Box RS-232 - 485 Interface Converters with DB9 connectors enable you to connect directly to high-speed RS-232 equipment. They are ideal if you have a computer with RS-232 connectors controlling equipment with an RS-485 interface. The RS-232 - RS-485 converter features built-in Silicon Avalanche Diode surge protection against data loss and equipment damage from transient surges. You can also "fine tune" impedence and echo characteristics for your individual application via switch settings.