Owner's manual

Technical Description
Sealevel Systems ULTRA-SIO Page 9
Technical Description
The Sealevel Systems Ultra-SIO provides the PC with two additional ground isolated RS-422/485 (P/N 3189) or
two non-isolated RS-422/485 (P/N 3089) serial ports for terminals, modems, printers, etc. Isolation is important in
installations where the equipment being connected to the PC is either far from the PC, or on a different power
transformer circuit. Ground loop current is a commonly neglected and misunderstood phenomena that leads to data
loss and the destruction of communications interfaces. The Ultra-SIO isolated boards provide up to 500 volts DC of
isolation.
The Ultra-SIO utilizes the 16550 UART. This chip features programmable baud rate, data format, interrupt control
and a 16 byte input and output FIFO. A full array of UART upgrades is also available offering larger FIFO’s.
Contact technical support for details.
Features
• Automatic RS-485 driver enable/disable allows card to appear to be RS-232 requiring no additional drivers
• ‘PAL’ option allows for unique OEM address selection
• ‘Shareable’ IRQs allow more than one port to share a single IRQ providing a polling type driver is used.
• IRQs 2/9-7, 10, 11, 12, 14, 15 supported
• 16550 buffered UARTs Standard
• 16 Bit address decode allows for easier integration
Connector Pin Assignments (DB 9 MALE)
Signal Name Pin # Mode
GND Ground 5
TX + Transmit Data Positive 4 Output
TX- Transmit Data Negative 3 Output
RTS+ Request To Send Positive 6 Output
RTS- Request To Send Negative 7 Output
RX+ Receive Data Positive 1 Input
RX- Receive Data Negative 2 Input
CTS+ Clear To Send Positive 9 Input
CTS- Clear To Send Negative 8 Input