The SIO4-104.2+2, Item Number 3544, is a PC/104 module that provides two RS-232 serial
interface ports for Ports 1 and 2 and two RS-422/485 serial interface ports for Ports 3 and 4. The
board is designed using the XR16C554 UART, which provides a 16-byte FIFO.
In addition to the standard XR16C554 UART, the XR16C854 (‘SE’ option) and the OX16C954
(‘SN’ option) are available. Both UARTS feature enhanced FIFOs (128 byte transmit and
receive) and both maintain compatibility with the XR16C554. The OX16C954 additionally
features a flexible clock prescalar (from 1 to 31.875), 9 bit protocol, and an isochronous mode.
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 SIO4-104.2+2 is designed to be used with a variety of Operating Systems including
Windows 98/NT/ME/2000/XP, Linux and DOS. The SeaCOM API (Application Programmer
Interface) included on CD with the SIO4-104.2+2 provides a variety of useful high-level function
calls implemented as a Windows dynamic link library (DLL) and as a Linux kernel module and
library. In addition to the API, SeaCOM includes sample code and utilities to simplify software
development.
Other Sealevel PC104 Serial Interface Products
ULTRA SIO-104 (Item Number 3550) Single Port RS-422/485
SIO-104 (Item Number 3551) Single Port RS-232
SIO.104+2 (Item Number 3502) Dual Port RS-232/422/485
C4-104.ULTRA (Item Number 3540) Four Port RS-232/422/485
SIO4-104.2+2 (Item Number 3542) Four Port RS-232
SIO4-104.2+2 (Item Number 3543) Four Port 422/485
The SIO4-104.2+2 is shipped with the following items. If any of these items is missing or
damaged please contact Sealevel for replacement.
SIO4-104.2+2 Adapter
Sealevel SeaCOM Software CD
Optional Items
Depending upon your application, you are likely to find one or more of the following items useful
for interfacing the SIO4-104.2+2. All items can be purchased from our website
(http://www.sealevel.com/
Cabling Options :
IDC 40 to (4) DB9 Male connectors, 8” in length - (Item Number CA228)
− Terminates the SIO4-104.2+2’s 40-pin header to four DB9M connectors.
DB37 Male to 6” IDC40 Ribbon Cable and (1) DB37 to (4) DB9 Males, 36” in
length - (Item Number CA110/CA143)
− This combination of cables also terminates the SIO4-104.232’s 40-pin
) or by calling 864-843-4343.
header to four DB9M connectors. The CA110 provides a bulkhead
mountable DB37 Male connector and the CA143 provides a DB37 to four
DB9 male connectors via a 36-inch ‘Spider’ cable.
IDC40 to 18” IDC40 Ribbon Cable and IDC40 to (4) DB9 Male Terminal Block
- (Item Number CA222/TB10)
− This combination of cables also terminates the SIO4-104.2+2’s 40-pin
header to four DB9M connectors via a bulk head mountable terminal block
assembly. It provides four DB9 male connectors that can easily be
integrated into the Sealevel Systems Relio line of embedded I/O servers.
DB9 Male to DB9 Female Optomux adapter (Item Number DB103)
− The DB103 is designed to convert a Sealevel DB9 Male connector to a
pinout compatible with AC24AT and AC422AT Opto-22 ISA bus cards.
This allows Optomux devices to be controlled from any Sealevel RS-422
board with a DB9 Male connector.
DB9 Male to DB9 Male Sony 207M adapter cable (Item Number CA190)
− This cable allows any Sealevel RS-422 adapter with a DB-9 to connect
directly to a Sony (or compatible) 207M "9 Pin" connector.
The SIO4-104.2+2 occupies 16 consecutive I/O locations. The DIP-switch (SW1) is used to set
the base address for these locations and the IRQ mode options. Be careful when selecting the base
address as some selections conflict with existing PC ports. The following table shows the
addressing options available. If different address options are required, please contact Sealevel
Systems Technical Support about a custom option.
SW1-1 SW1-2 SW1-3 Port 1 Port 2 Port 3 Port 4
Off Off On 300 310 320 330
Off On Off 400 410 420 430
Off On On 500 510 520 530
On Off Off 600 610 620 630
On Off On 1500 1510 1520 1530
On On Off 3220 3230 3240 3250
On On On 4220 4230 4240 4250
Interrupt Modes
DIP-Switch positions ‘S’ and ‘M’ on switch SW1 selects the interrupt mode for each adapter.
With the ‘S’ selected, the adapter is in a (S)hared interrupt mode, which allows more than one
adapter to access a single IRQ.
‘M’ indicates the inclusion of a 1K-ohm pull-down resistor required on one adapter when sharing
interrupts.
Set the switch to ‘S’ for shared interrupt mode on all adapters sharing an IRQ. On one of the
adapters sharing an interrupt set the switches for both ‘S’ and for ‘M’. This provides the pulldown resistor circuit that makes sharing IRQs possible. If you are using more than one
compatible adapter in a bus you should only have one adapter set to ‘M’.
IRQ Selection
The SIO4-104.2+2 has an interrupt selection jumper, which should be set prior to use, if an
interrupt is required by your application software. Consult the user manual for the application
software being used to determine the proper setting.
The SIO4-104.2+2 utilizes a 14.7456 MHz oscillator. This is eight times faster than the standard
COM: port oscillator, which typically is 1.8432 MHz. This allows the adapter to achieve a
maximum data rate of 921.6Kbps. The following sections outline the baud rate calculations and
instructions for achieving your desired baud rate.
Baud Rates and Oscillator value
The following table shows some common data rates and the rates you should choose to achieve
them when using the SIO4-104.2+2. If the O/S of choice is Windows 95/98/ME/2000/NT/XP, the
oscillator value (14.7456 MHz) should be entered into the ‘Advanced Tab’ on 95/98/Me/2000/XP
Device Manager applet. Typically this is done automatically when the Sealevel Software driver is
loaded.
When using Windows NT, the ‘Advanced Ports’ applet in the Control Panel should be launched
and the oscillator value entered manually in the ‘Advanced’ tab, or all data rates will be eight (8)
times the selected rate. For example if a data rate of 19.2Kbps is selected, the actual data rate will
be 153.6Kbps.
When using any other OS (i.e. Linux, or QNX) the following table should be used.