Four Port RS-422/475 USB Adapter RS-422 and RS-485 serial interface Four independnt serial ports Capable of data ranges up to 115.2 kbps Compatible with USB Specification 1.1 Plug & Play and Hot Swap capability Device is enumerated as standard COM ports Full-duplex or half-duplex operation possible Automatic transceiver control in half-duplex operation possible Automatic transceiver control in half-duplex mode with DTR or RTS line Bus powered; no external power supply required
The QSU-200/300 provides four indepent asynchronous serial interfaces to a PC via the USB port. Each of these interfaces may be used for either RS-422 or RS-485 communication. The adapter comes standard with four independent 16550 UARTs containing 16-byte FIFOs. These FIFOs, along with the FIFOs in the USB microcontroller, help to relieve the CPU of excessive interrupts by buffering received and transmitted data, making each channel capable of data rates up to 115.2 kbps.
To allow the continued use of existing application software designed for traditional serial adapters, the QSU-200/300 enumerates itself as standard COM ports. Thus, users can continue employing their present serial devices, while at the same time taking advantage of the benefits provided by USB. For instance, users need not concern themselves with resource issues that exist on the ISA bus when adding new devices such as selecting I/O address and IRQ.
Another advantage of USB is Plug & Play capability; the user merely plugs a device in and it configures itself for operation. An additional user friendly service is hot-swap capability; the computer need not be powered down befor plugging in a new device.
The QSU-200/300 is completely compatible with USB specification 1.1. It is bus-powered, so no external power supply is needed. Support is provided for Windows 98 and Windows 2000.