The BLS 4228S is a high-performance RS422/485 card with 16C550-style UARTs that feature 16-byte transmit and receive buffers to help guard against loss of data in your busy system. The card may be addressed as COM1: to COM4: or any other I/O address you choose from 000 up to 3F8 hex. The backplate has eight standard DB-9 male (9-pin) connector.
All ports are capable of operating at speeds up to 460kbaud simultaneously, making this card ideal for high-speed applications such as ISDN modems.
Interrupt Sharing: The Key to Adding Many Serial Ports
The powerful interrupt feature allows multiple ports on a single card to use the same interrupt. With this technology, up to eight ports in one system can share one interrupt. Any of eleven interrupt choices are available for each port. The card is jumper-selectable for compatibility with protocols used by Digi®. This functionality provides drop-in replacement capability at reduced cost. Because each port's address may be defined individually, you don't have to worry about address conflicts the way you would with cards that use 32- and 64-byte blocks for addressing. Our serial cards are compatible with all application software that communicates with a standard serial port using an 8250 or 16C450 UART (the UARTs which virtually all PC's use for serial ports). This includes compatibility with DOS, Windows 3.x/95/98/NT/ME/2000/XP, OS/2, UNIX, and XENIX. An NT setup disk is provided with all 4- and 8-port units to make your Windows NT installation and registry modifications a breeze. RS-232 cards support the standard RS-232 interface and all the above mentioned features; they're DTE/DCE selectable so no special cables are required. Each port supports all handshake and modem control lines, including: TXD, RXD, RTS, CTS, DSR, DCD, DTR, and RI.
Drivers are automatically and instantly disabled (and receivers enabled) after transmission of the stop bit. Drivers and receivers may also be controlled with data bits 0 and 1 by writing to the base address+7 for the port (MetraByte COM-485 protocol compatible). RTS and CTS flow control is supported as well. Convenient on-board jumpers allow for 220-ohm termination as needed for each driver and receiver.