Impulse 3603 - Manual (Page 5)

Technical Description
Sealevel Systems PC-SIO-232 Page 3
Technical Description
The PC-SIO-232 provides one RS-232 serial port utilizing the 16550 UART (Universal Asynchronous Receiver
Transmitter).
The PC-SIO-232 is addressable as any COM: port (e.g. COM1:, COM2:, etc.) The PC-SIO-232 provides for
selectable IRQs (3,4,5,7,9,10,11,12,15). I/O address and IRQ combinations are very flexible, and information on
selecting these combinations is available in the Card Services Documentation and the supplied software. Please
refer to the software supplied with the PC-SIO-232 for any manual updates, corrections and software specific
changes
.
Each COM: Port requires a minimum of one block of eight I/O addresses. For example, COM1: is usually hex
address 3F8. 3F8 is the base address, and the COM: ports extend through 3FF. In most applications, each COM:
port will utilize one IRQ.
Connector Pin Assignments for RS-232 (DB-25 and DB-9 Male)
Signal Name DB-25 DB-9* Mode
GND Ground 7 5
TD Transmit Data 2 3 Output
RTS Request To Send 4 7 Output
DTR Data Terminal Ready 20 4 Output
RD Receive Data 3 2 Input
CTS Clear To Send 5 8 Input
DSR Data Set Ready 6 6 Input
CD Carrier Detect 8 1 Input
RI Ring Indicator 22 9 Input
* Note: These assignments meet EIA/TIA/ANSI-574 DTE for DB-9 type connectors.
Technical Note: Please terminate any control signals that are not going to be used. The most common way to do this
is connect RTS to CTS and RI. Also, connect DCD to DTR and DSR. Terminating these pins, if not used, will help
insure you get the best performance from your adapter.