The 7804 is a multi-interface, eight port, Universal Bus (3.3V or 5V) compatible PCI adapter. Offering eight individual field-selectable RS-232, RS-422, or RS-485 channels, the 7804 delivers ultimate flexibility for expanding serial communications.
The 7804 supports standard PC data rates and boasts a top speed of 921.6K bps. The board is designed using the XR16C864 UART, which provides a 128-byte FIFO, eight times larger than boards designed with 16C550 compatible parts. The larger buffers allow error free operation even in high-speed applications. In RS-485 mode the board provides automatic control of the RS-485 driver enable for trouble free network master arbitration. Additionally, RS-485 network termination, critical to robust multi-drop communication, can be selectively added to the circuit via DIP-switches.