User Manual

Technical Description
Sealevel Systems ULTRA-485 Page 11
Technical Description
The ULTRA 485 utilizes the 16550 UART. This chip features programmable
baud rates, data format, interrupt control and a 16-byte input and output FIFO. A
full array of advanced UARTS is also available.
The unique feature of the ULTRA 485 is the ability to be RS-485 compatible
without the need for special software or drivers. This is especially useful in
Windows, Windows NT, and OS/2 environments where the lower level I/O
control is abstracted from the application program. Which means that the user
can effectively use the ULTRA 485 in a RS-485 application with existing (i.e.
standard RS-232) software drivers.
Features
• Automatic RS-485 driver enable/disable allows card to appear to be
standard COM: port requiring no additional drivers
• ‘PAL’ option allows for unique OEM address selection
• ‘Shareable’ IRQs allow more than one port to share a single IRQ provided a
polling type driver is used
• IRQs 2/9-7, 10, 11, 12, 14, 15 supported
• 16550 buffered UART standard
• 16 Bit address decode allows for easier integration