Black Box RS-232 Address Selection, Binary, Typically COM1=3F8h COM2=2F8h COM3=3E8h COM4=2E8h

CHAPTER 3: Address Selection

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.”

A9 A3 EN

0

1

ON

OFF

1 2 3 4 5 6 7 8

5