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© Sealevel Systems, Inc. 3541 Manual | SL9150 12/2022
Introduction
Overview
The
C4-104.ULTRA
provides a PC/104 serial interface module with four software-selectable RS-
232/422/485 ports. RS-232, RS-422, or RS-485 mode may be selected independently via software
command for each of the four ports, eliminating the need for setting jumpers or DIP-switches. The board
is designed using the XR16C864 UART, which provides a 128-byte FIFO, 8 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
C4-104.ULTRA
offers automatic control of the RS-485 driver enable for
trouble free network master arbitration. Additionally, the
C4-104.ULTRA
allows RS-485 network
termination, critical to robust multi-drop communication, to be selectively added to the circuit via a simple
software command.
The RS-232 compatibility allows for connection to devices utilizing the RS-232 electrical interface, such as
modems, data-entry terminals, and plotters.
RS-422 provides excellent communications for long distance device connections up to 4000ft., where noise
immunity and high data integrity are essential.
RS-485 is optimized for ‘Multi-Drop’ or ‘Party-line’ operations selecting data from multiple peripherals (as
many as 31 devices can be connected on an RS-485 bus). The
C4-104.ULTRA
is optimized for RS-485 with
automatic driver enable, and automatic suppression of RS-485 ‘Echo’ as options, further simplifying
integration.
Factory Default Settings
The
SIO-104
factory default settings are as follows:
Base
Address
IRQ
Port 1
280
5
