232XSSD43800 Manual
13
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
Another option available on the 232XSSD4 is the slave ports set
up as RS-422 ports. This means that the driver and receiver will be
enabled all the time. RS-422 allows point-to-point operation or up to
10 receive only units up to 4000 feet on two pair of lines.
Port Expansion Bus
The number of serial ports on the 232XSSD4 can easily be
expanded to a maximum of sixty-eight ports. Fifteen Port Expander
units (232PE) can be added to the 232XSSD4 by simply connecting
the 232PE units to the Port Expansion Bus. Each Port Expander
unit (232PE) adds four additional serial ports. The Port Expansion
Bus connects each port to the electronic switch control circuit in the
232XSSD4. In order for the 232XSSD4 to select a port on a Port
Expander unit, each unit must be assigned its own unique address
from "1" to "15". These addresses are switch selectable by the user.
Refer to the 232PE manual for more information.
Smart Switch Operation
The 232XSSD4 has two modes in which it can select ports,
smart switch, and smart switch/port combiner.
Smart Switch Mode
Position 6 of SW1 must be in the off position to enable this
mode. Refer to Figure 2 and Table 1. The Smart Switch is a listen
only device. It constantly monitors the serial data received on the
Master port for a command control string. A command can switch
on or switch off any desired port. The command control string can
be configured as a three-character command or a four-character
command. In this mode Port "A" will be selected at power up.
Three Character Command String
The first character is user defined by setting SW2, an eight-
position DIP switch. SW2 is programmed at the factory to the ASCII
character STX (decimal 2). The second character represents the
hexadecimal address of the Smart Switch where the desired port is
located. The address for the 232XSSD4 is always zero (0). The
address of the port expanders (232PE) can be from 1 through 15
(ASCII-HEX "1" through "F"). The third character is the ASCII upper
case letter that represents the desired port. Letters "A", "B", "C",
"D", "E", "F", "G" or "H" (decimal 65, 66, 67, 68, 69, 70, 71, or 72
respectively) are used to select ports on the 232XSSD4. Letters "A",
"B", "C", or "D" (decimal 65, 66, 67, or 68 respectively) are used to
select ports on the 232PE.
