5
CHAPTER 3: Address Selection
NOTE
Be sure to set the address selections and jumper options before
installation.
Each serial port on the Four Port RS-232 Serial Interface occupies 8 con-
secutive I/O locations. DIP switch SW4 sets the base address for Port 1, SW3
for Port 2, SW2 for Port 3, and SW1 for Port 4. Be careful when selecting the
base address as some selections conflict with existing PC ports. The following
table shows several examples that usually do not cause a conflict.
Address Binary Switch Position Setting
Hex A9 A0 1 2 3 4 5 6 7
280-287 1010000XXX OFF ON OFF ON ON ON ON
2A0-2A7 1010100XXX OFF ON OFF ON OFF ON ON
2E8-2EF 1011101XXX OFF ON OFF OFF OFF ON OFF
2F8-2FF 1011111XXX OFF ON OFF OFF OFF OFF OFF
3E8-3EF 1111101XXX OFF OFF OFF OFF OFF ON OFF
300-307 1100000XXX OFF OFF ON ON ON ON ON
328-32F 1100101XXX OFF OFF ON ON OFF ON OFF
3F8-3FF 1111111XXX OFF OFF OFF OFF OFF OFF OFF
Typically COM1:=3F8h; COM2:=2F8h; COM3:=3E8h; COM4:=2E8h
The following illustration shows the correlation between the DIP-switch
setting and the address bits used to determine the base address. In the figure
below, the address 300 hex through 307 hex is selected (300 hex =11 0000
0XXX in binary representation, where X is a non-selectable address bit). Note
that setting the switch ON (or closed) corresponds to a “0” in the address,
while leaving it OFF (or open) corresponds to a “1.”
