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232XS2497 Manual 13
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5109
Expansion Mode
The number of serial ports on the 232XS5 can easily be
expanded to a maximum of seventeen ports. Up to four 232XS5
units may be cascaded in expander mode. Each unit address adds
four additional serial ports to the five on unit address “A”. Port C is
used as the expansion port that connects to the follow-on master-
port for switch units addressed “B” thru “D”. Expansion Switch unit
address “A” is the last Switch in the chain.
Expander mode is selected when jumper “JP6-B” is OFF
(removed.) In Expander mode, the 232XS5 is constantly looking for
a four character preamble code by monitoring the data that is being
received on the master port from the host device. The 232XS5
requires a four character preamble code to turn on and off a port.
The first character must be the ASCII escape character (decimal
27). The second character is user programmable by setting
dipswitch “SW2”. “SW2” comes from the factory programmed to the
ASCII character STX (decimal 2). The third character is the
Expansion Switch Unit Address character “A” through “D”. The
fourth character should be the ASCII upper case letters "A", "B", "C",
"D" or “E” (decimal 65, 66, 67, 68 or 69 respectively) to select those
ports. To turn off the selected port the third character should be the
ASCII EOT character (decimal 4). For instance, to turn on port B of
Expansion Switch unit address C, you would send:
ESC STX C B
If you were writing a program in BASIC to control the Smart
Switch you would form a string like this:
SWB$ = CHR$(27) + CHR$(2) + "C" + ”B”
Master
Port
Expansion
Port
17-Port Cascaded Expansion Mode
Address D
C
C
Address C
Slave
Port
B
Slave
Port
A
Slave
Port
A
Address B
Slave
Port
Slave
Port
A
B
Slave
Port
B
C
Slave
Port
DE
Slave
Port
E
Slave
Port
Expansion
Port
E
Slave
Port
D
Slave
Port
Expansion
Port
Slave
Port
D
C
Slave
Port
Slave
Port
Slave
Port
Address A
AB
ED
Slave
Port
Slave
Port