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Documentation Number 232D4SS84502 Manual 13
B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Comm. Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
Another option available on the 232D4SS8 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.
Smart Switch Operation
The 232D4SS8 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 232D4SS8 is always zero (0). 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 232D4SS8.
Example 1: To turn on port E of the 232D4SS8 (address zero) with
ASCII STX (2 decimal) character set as the user
defined character.
Send to the Master Port: STX 0 E
(2 48 69 decimal)
When you are done with a port you can either select a new one
directly or turn off the selected port and then turn on the next one. It
is recommended that the selected port be turned off before selecting
the next port. For this reason, if port A is currently selected and a
command is sent to select port E, the command characters (STX 0
E) will pass through to the port A device and because characters "0"
and "E" are printable they may appear on that device.