User`s guide

Technical Description
OMG-ISO-COMM Page 9
Technical Description
The OMG-ISO-COMM provides the PC with two or four additional ground
isolated RS-422/485/232 or two or four non-isolated RS-422/485 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 OMG-ISO-COMM isolated boards provide up
to 500 volts DC of isolation.
The OMG-ISO-COMM utilizes the 16550 UART. This chip features
programmable baud rate, data format, interrupt control and a 16 byte input and
output FIFO. Also available as an option is the 16C650 UART that provides a
deeper FIFO (32 bytes) and enhanced clocking features.
• Two / four serial ports with RTS and CTS modem control signals
• Individually selectable port addresses
• Individually selectable interrupt (2-7, 10, 11, 12, and 15 )
• Multiple cards can share the same IRQ signal
• DB-9 male connectors
• Software available for interrupt buffering
• OMG-ISO-COMM-1 Four Port Isolated RS-422/485
• OMG-ISO-COMM-3 Two Port Isolated RS-422/485