16
4-PORT RS-232 PCI AND HS PCI SERIAL ADAPTERS
The ISP is at Base+7 on each port (Example: Base = 280 Hex, Status Port = 287,
28F… etc.). The adapter will allow any one of the available locations to be read to
obtain the value in the status register. All four status ports on the adapter are
identical, so any one of the four can be read.
Example: This indicates that Channel 2 has an interrupt pending.
Bit Position:
7
6
5
4
3
2
1
0
Value Read:
0
0
0
0
0
0
1
0
NOTE
Bits 4–7 are not driven and can report back as a 1 or a 0. Most
application software will mask the unused bits to determine if an
interrupt is pending.
5.3 Connector Pin Assignments
Table 5-1. DB25 (RS-232 DTE).
Signal
Name
Pin #
Mode
GND
Ground
7
—
TD
Transmit Data
2
Output
RTS
Request To Send
4
Output
DTR
Data Terminal Ready
20
Output
RD
Receive Data
3
Input
CTS
Clear To Send
5
Input
DSR
Data Set Ready
6
Input
DCD
Data Carrier Detect
8
Input
RI
Ring Indicator
22
Input
