B&B Electronics 232BSS4 User manual

Manual Documentation Number: 232BSS4-0812
B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
Buffered Smart Switch
Model 232BSS4
Documentation Number: 232BSS4-0812
This product designed and manufactured in Ottawa, Illinois USA
of domestic and imported parts by
707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350 USA
Phone [phone] -- General Fax [phone]
Phone [phone] -- General Fax [phone]
Website: www.bb-elec.com
Sales e-mail: [email protected]om -- Fax [phone]
Technical Support e-mail: [email protected] -- Fax [phone]
European Headquarters
B&B Electronics
Westlink Commercial Park -- Oranmore, Co. Galway, Ireland
Phone [phone] -- Fax [phone]
Website: www.bb-europe.com
Sales e-mail: [e-mail]
Technical Support e-mail: [email protected]
B&B Electronics Mfg. Co. Inc. -- July 2007

B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
This document contains information that is proprietary and confidential to B&B
Electronics Mfg. Co. Inc. The methods described herein are for the exclusive use of
B&B Electronics authorized personnel. Any unauthorized use or dissemination of the
information contained in the document is strictly forbidden.

Manual Documentation Number: 232BSS4-0812 Table of Contents i
B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
Table of Contents
CHAPTER 1 –INTRODUCTION............................................................1
SPECIFICATIONS........................................................................................2
DEFAULT PARAMETERS ............................................................................2
CHECKLIST................................................................................................3
CHAPTER 2: OPERATION....................................................................5
SYMBOLS AND CONVENTIONS...................................................................5
LED INDICATORS......................................................................................5
PORT CONFIGURATIONS............................................................................6
SMART SWITCH ONLY MODE....................................................................7
AUTO SELECT/SMART SWITCH MODE.....................................................14
USING THE 232BSS4 AS A BUFFERED SPLITTER/COMBINER ...................16
BACK TO BACK OPERATION (MUX/DEMUX) ............................................17
CASCADING MULTIPLE SWITCHES ..........................................................18
CHAPTER 3: PORT CONNECTIONS ................................................21
DTE/DCE EXPLANATION .......................................................................21
CHAPTER 4: SETUP SOFTWARE.....................................................23
INTRODUCTION .......................................................................................23
CONNECTION...........................................................................................23
SOFTWARE INSTALLATION......................................................................24
SOFTWARE UNINSTALL...........................................................................24
SETUP TUTORIAL ....................................................................................25
APPENDIX A: ASCII CHARACTER CODES.....................................1
APPENDIX B: CABLE CHARTS...........................................................1
CHART B.1. DTE (PC) DB25 CONNECTOR TO MASTER PORT..................1
CHART B.2. DTE (PC) DB9 CONNECTOR TO MASTER PORT....................1
CHART B.3. DCE (MODEM)DB25 CONNECTOR TO MASTER PORT .........3
CHART B.4. DCE (MODEM)DB9 CONNECTOR TO MASTER PORT ...........3
CHART B.5. PORTS A-D(DTE) TO DTE (PC) DB25 CONNECTOR..........4
CHART B.6. PORTS A-D(DTE) TO DTE (PC) DB9 CONNECTOR............4
CHART B.7. PORTS A-D(DTE) TO DCE (MODEM)DB25 CONNECTOR .4
CHART B.8. PORTS A-D(DTE) TO DCE (MODEM)DB9 CONNECTOR ...5
APPENDIX C: BLOCK DIAGRAM.......................................................1
APPENDIX D: DECLARATION OF CONFORMITY.........................1

ii Documentation Number 232BSS4-0812m
B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com

Documentation Number 232BSS4-0812m 1
&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
Chapter 1 –Introduction
The 232BSS4 provides communications to four devices from one serial
port. Each port uses a dedicated UART and includes an 8K byte transmit
buffer and an 8K byte receive buffer (16K bytes total). Each port can be
independently configured for data rate, data format, and protocol. The
Master port can send and receive data from one of the Slave ports while the
other Slave ports continue to buffer data. The Master device can also
broadcast the same message to two or more Slave ports at once.
The 232BSS4 can be configured to send data automatically to the
Master port from each of the Slave ports when data is present with an
optional preamble identifying the port. It can also provide two-way
communications between the Master port and one Slave port at a time.
Switching and control is done through user-defined three or four character
command strings. All control sequences are removed from the data stream,
making the switch transparent to the Slave devices. The PC setup software
provided walks the user through all possible parameters.
Switches can be cascaded to expand the 232BSS4 to more than four
ports. Two units can also be used back-to-back to provide automatic
connection between devices over a single data channel. LEDs on the
232BSS4 indicate when the unit is powered up and which port is selected to
send data to the Master port.

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Specifications
Model: 232BSS4
Interface: RS-232 asynchronous
Data Format: 7 or 8 data bits, even, odd, or no parity
(Master does not support 7 data bits with no
parity)
1 stop bit (fixed)
Data Rate: 1200 to 115.2 kbps
Flow Control: Hardware(RTS/CTS) or None
Power Requirements: +10 to +15 VDC @ 60 mA max.
Power Connector: 2.5 mm phone jack (+ tip)
Recommended Supply: B&B Model 232PS (Sold separately)
Operating Temperature:0º to 70º C
Data Connectors: Master DB25 female (DCE)
Slaves DB9 male x 4 (DTE)
Dimensions: 7.5 x 4.6 x 1.2 in. (19.0 x 11.7 x 3.0 cm)
Setup Software: PC compatible,
Windows 95/98/NT/2000/XP/Vista
Supplied Accessories: CDROM with Setup Program
Instruction Manual
Default Parameters
When shipped, the 232BSS4 comes set up for the following
parameters:
Auto Select mode OFF
DTR NOT required to accept commands
THREE character command
Char1 = ESC (Decimal 27)
Char2 = STX (Decimal 2)
Char3 = “0” (Not Used)
Port Time = 1,000mS (not used)
Inactivity Time = 500mS (not used)
All ports 9600 Baud
All ports 8 Data Bits
All ports No Parity
All ports No Hardware Handshake required
Ports A-D No preamble
Port A selected to Transmit & Receive on Power-up
Refer to the following sections of the manual for what each of these
parameters means and how they can be changed.

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Checklist
Examine the shipping carton and contents for physical damage. If
damage is found, file a claim with the shipper immediately.
The following equipment should be in the shipping carton:
1. RS-232 Buffered Smart Switch model 232BSS4
2. Instruction Manual
3. (2) 3.5" floppy disks
If any of the items above are not in the shipping carton contact the
shipper immediately.

4Documentation Number 232BSS4-0812m
B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com

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&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
Chapter 2: OPERATION
Symbols and Conventions
Throughout this chapter of the manual, the following symbols and
conventions will be used to clarify what type of data we are addressing.
Items enclosed in {brackets} will denote one byte.
A character in “quotes” will normally denote a printable ASCII
character. A byte described in ALL CAPS is the ASCII description
of a non-printable character. The abbreviation dec will denote a
decimal value. The lower case letter h will be used to show a Hex
value.
Items in italics are optional items only used in certain
configurations. The instances when these items are required will be
explained in the text.
LED Indicators
The 232BSS4 has five LED indicators. The first, labeled “+12 VDC
POWER” indicates that power is applied to the switch. The other four,
labeled “PORT A” to “PORT D” indicate which Slave port is currently
selected to transmit to the Master.
In Smart Switch Only mode, the port LEDs indicate which port was
selected through the Select Port command. In Auto Select mode, the port
LEDs indicate which port is currently sending to the Master. No indication
is provided to display which Slave port is currently receiving from the
Master.

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Port Configurations
The 232BSS4 provides a dedicated UART to all five ports. This allows
any port to be individually configured for baud rate, number of data bits,
parity, and hardware (RTS/CTS) handshaking. Configuration of all the
ports is done through the setup software.
Baud Rate:
Each port is configurable for the following baud rates:
1200
2400
4800
9600
19.2K
38.4K
57.6K
or 115.2 kbps
Data Bits:
Each port can be configured for Seven or Eight data bits.
Note: If the Master and Slaves are set up differently, the port set for
Seven data bits cannot transmit the eighth bit.
Parity:
Each port can be configured for Even, Odd, or No parity. Because
the Master port uses a slightly different UART, it is not capable of
receiving only seven bits, thus seven data bits with no parity is not
allowed on the Master port. All other configurations are possible.
Stop bits:
Each port uses 1 stop bit. This value is currently fixed and can not
be changed in the setup software.
Hardware(RTS/CTS) Handshaking:
Each port can be configured to hold data until its input handshake
line goes high. On the Master port, pin four (RTS) would have to be
held high by the host device in order for the 232BSS4 to send data. On
the Slaves, pin eight (CTS) needs to be held high by the Slave device
for the 232BSS4 to send data. The connected devices can prevent data
from being sent from the 232BSS4 by holding their corresponding
handshake lines low.

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Smart Switch Only Mode
Description:
Smart Switch Only mode is used when the host device connected
to the Master port initiates all communications with the Slave devices. To
use the 232BSS4 as a Smart Switch Only, Auto Select is left unchecked in
the setup software.
In Smart Switch Only mode, the 232BSS4 is constantly looking for a
command sequence by monitoring the data that is being received on the
Master port from the host device. This command can tell the 232BSS4 to
connect the Master port to a single Slave port, send data to one or more
Slave ports at once, discontinue communications with all Slave ports, or
ignore commands for a specific length of time.
All command characters are buffered until the full command sequence
is received. If the 232BSS4 recognizes the data stream as a command
sequence, the sequence is not passed through the switch.
Options:
Initial Connections:
Upon power-up, the 232BSS4 can be initialized to allow the Master
access to any of the Slave ports without any commands sent. The
Master to Slave and Slave to Master initialization are each
independently configurable through the setup software. The Master can
also be set to broadcast to any or all of the Slave ports on power-up. If
no ports are selected to be initialized on power-up, the 232BSS4 will
wait for a switching command before allowing the Master access to any
of the Slaves.
3 or 4 Character Command:
The 232BSS4 commands can be set to be either three or four
characters long. The first two or three characters can be programmed to
any value through the setup software. The third or fourth character is
the actual command.
Thus the command sequence would look like:
{Char1}{Char2}{Char3}{Command Character}
Char1-3 would be defined by the user through the setup software.
Char3 would only be sent if the 232BSS4 was set up for a four character
command.

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Command Summary:
Three Character Command Format:
Char1
Char2
Command Char
Control Char
Control Char is only needed for Tx Only, Clear Buffer, and Ignore
Commands
Four Character Command Format:
Char1
Char2
Char3
Command Char
Control Char
Control Char is only needed for Tx Only, Clear Buffer, and Ignore
Commands
Table 2.1 - 232BSS4 Command Summary
Function
Command
Char.
Control
Char.
Comments
Select Port A Tx & Rx
“A”
None
Switching Command
Select Port B Tx & Rx
“B”
None
Switching Command
Select Port C Tx & Rx
“C”
None
Switching Command
Select Port D Tx & Rx
“D”
None
Switching Command
Deselect All Ports
EOT
None
Switching Command
Tx Only to Specific Ports
“S”
Dec 0 to 15
Use to Broadcast
Clear Buffer on Specific
Ports
“X”
Dec 0 to 15
Clear the Receive
Buffer
Ignore Commands
“T”
“0” to “9”
Sets Timer Value
Values in quotes “” are ASCII characters.
Dec. is an abbreviation for decimal value.
Command Explanation:
Where applicable, this section will provide an example of how to
create the command strings in Visual Basic. Other programming languages
may require a slightly different syntax, but the examples given should
provide enough information to port to other languages. For our examples,
we will use the default settings of the switch:
3 Character Command Sequence
Character 1 set to ASCII ESC character (Decimal 27)
Character 2 set to ASCII STX character (Decimal 2)
If you choose to use a four character command sequence, just add
another character between the second programmable character and the
command character in the command string.

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Commands:
Select Port A to transmit and receive –“A”
Select Port B to transmit and receive –“B”
Select Port C to transmit and receive –“C”
Select Port D to transmit and receive –“D”
The Select Port commands turn on the selected port for both
transmit and receive operations. Once the command is received by the
switch, any data that had been buffered from the selected Slave device
will be sent to the Master. Any data received on the Master port that is
not a valid command sequence will be passed to the selected Slave port
until another command is received.
For instance, to send and receive data from port B, send:
{Char1}{Char2}{Char3}”B”
VB Example:
SwitchB$ = CHR$(27) & CHR$(2) & “B”
Turn Off all selected ports –ASCII EOT character (decimal 4)
The Turn Off command deselects all ports. No ports will transmit
or receive to/from the Master port until another command is received by
the Master port.
The full command sequence to disable all ports is:
{Char1}{Char2}{Char3}EOT
VB Example:
OFF$ = CHR$(27) & CHR$(2) & CHR$(4)
Send Only to specific ports –“S” + one control byte specifying which ports
to send.
The Send Only command will tell the 232BSS4 which Slave ports
to send the following data to. This command can be used to broadcast
data to more than one port at a time. The Slave port that is sending to
the Master is not affected.
The lowest four bits of the control byte tell the 232BSS4 which
ports should receive the following data. Bit 0 represents port A, Bit 1
represents port B, Bit 2 represents port C, and Bit 3 represents port D.
In decimal, this is represents a value of 1, 2, 4, and 8 respectively. To
turn on more than one port, the decimal equivalents of each port are
added together to give the final byte.

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A summary of the control characters for each combination of ports
is given in Table 2.2.
For instance, to broadcast to ports B & C, send:
{Char1}{Char2}{Char3}”S”{Decimal 6}
(B = 2, C = 4, 2 + 4 = 6)
VB Example:
BroadcastBC$ = CHR$(27) & CHR$(2) & “S” & CHR$(6)
Clear Receive Buffer –“X” + one control byte specifying which ports’
buffers to clear.
The Clear Buffer command will tell the 232BSS4 which Slave
ports’ receive buffers to purge. If the Master device is only interested in
the most recent data from the Slaves, this command can be used to
delete old data from one or more of the Slave port buffers before it is
sent to the Master.
The lowest four bits of the control byte tell the 232BSS4 which
ports’ buffers to purge. Bit 0 represents port A, Bit 1 represents port B,
Bit 2 represents port C, and Bit 3 represents port D. In decimal, this is
represents a value of 1, 2, 4, and 8 respectively. To clear more than one
buffer with a single command, the decimal equivalents of each port
would be added together to give the final byte.
A summary of the control characters for each combination of ports
is given in Table 2.2.
For instance, to clear the receive buffer on ports A & D, send:
{Char1}{Char2}{Char3}”S”{Decimal 9}
(A = 1, D = 8, 1 + 8 = 9)
VB Example:
ClearAD$ = CHR$(27) & CHR$(2) & “X” & CHR$(9)

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Table 2.2: Send Only and Clear Buffer Control Characters
Ports to Transmit or
Clear Receive Buffer
Binary Value
(x = Don’t Care)
Decimal
Value
ASCII
Character
None
xxxx0000
0 or 64
“@”
A Only
xxxx0001
1 or 65
“A”
B Only
xxxx0010
2 or 66
“B”
A & B
xxxx0011
3 or 67
“C”
C Only
xxxx0100
4 or 68
“D”
A & C
xxxx0101
5 or 69
“E”
B & C
xxxx0110
6 or 70
“F”
A, B, & C
xxxx0111
7 or 71
“G”
D Only
xxxx1000
8 or 72
“H”
A & D
xxxx1001
9 or 73
“I”
B & D
xxxx1010
10 or 74
“J”
A, B, & D
xxxx1011
11 or 75
“K”
C & D
xxxx1100
12 or 76
“L”
A, C, & D
xxxx1101
13 or 77
“M”
B, C, & D
xxxx1110
14 or 78
“N”
A, B, C, & D
xxxx1111
15 or 79
“O”
Note: The 232BSS4 ignores the upper 4 bits of the control byte. If the
Master device is incapable of sending characters outside the printable
ASCII range, decimal 64 can be added to each of the control bytes and the
switch will operate properly.
Ignore Commands –“T” + one control byte specifying the length of time to
ignore commands.
The Ignore Commands command tells the 232BSS4 to ignore all
commands from the Master device for a specific amount of time. This
command is useful if the data coming from the Master device may
contain switching commands. By switching to a port, then sending the
Ignore Commands command, all data received on the Master port of the
232BSS4 will be passed directly to the selected Slave port without
checking for a command sequence until the programmed time has
elapsed. The control byte at the end of the command tells the 232BSS4
how long to ignore commands from the Master device. This byte is
ASCII “0” – “9” (48 – 57 Decimal). Timer values for each Control byte
are given in Table 2.3.

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For instance, to ignore switching commands for 30 Seconds, send:
{Char1}{Char2}{Char3}”T””7”
VB Example:
Ignore30s$ = CHR$(27) & CHR$(2) & “T” & “7”
Table 2.3 - Timer Values
Control Byte
(ASCII)
Control Byte
(Decimal)
Timer Setting
“0”
48
Timer disabled
“1”
49
10ms
“2”
50
25ms
“3”
51
100ms
“4”
52
500ms
“5”
53
1 s
“6”
54
5 s
“7”
55
30 s
“8”
56
1 min.
“9”
57
5 min.
Binary file transfer:
Two methods are provided in the 232BSS4 to prevent inadvertent
switching during a transfer of raw data bytes from the Master device to one
or more Slaves. Because the user doesn’t know if a command sequence is
imbedded in the raw data, the switch must be set to ignore commands.
Note that these procedures are not needed if the binary file will be
transferred from the Slave devices to the Master device. No switching
commands are used in the 232BSS4 with data from this direction, so no
inadvertent switching can occur.
Method1 –Ignore Commands For a Specific Length of Time
The first method is to ignore commands for a specific length of
time. This method is useful if the user knows how long the transfer will
take. The Master would first send the command to connect it to the
Slave port(s) that are to receive the data. Then the Master device would
send the “T” command along with the byte telling the 232BSS4 how
long to ignore commands. Once this is sent, data can be transferred to
the Slave(s) without the 232BSS4 looking for command sequences.
Once the timeout has been reached, the switch will continue looking for

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commands and the Master can initiate the next communications
sequence.
Example:
For a binary transfer from the Master to the device on Port A that
will take less than one second to complete
Send Select Port A Command: {Char1}{Char2}{Char3}”A”
Send Ignore Commands Command:
{Char1}{Char2}{Char3}”T””5”
Send the Binary File
Wait for the timeout period
Repeat for the next file/port
Method2 –Ignore Commands Using DTR
The second method of ignoring command sequences is to set the
232BSS4 to ignore commands if DTR is low from the Master device.
This option is enabled through the setup software. This method is useful
if the length of the binary file transfers are not known. The user would
first raise DTR on the Master device, then send the command to connect
it to the Slave port(s) that are to receive the data. Once the command is
sent, the Master device would then lower DTR and transmit the data.
The 232BSS4 would ignore command sequences and pass them through
to any connected ports until DTR was raised.
Example:
For a binary transfer from the Master to the device on Port A
Raise DTR on the Master Device
Send Select Port A Command: {Char1}{Char2}{Char3}”A”
Lower DTR on the Master Device
Send the Binary File
Repeat for the next file/port

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Auto Select/Smart Switch Mode
Description
Auto Select mode allows the Slave devices to initiate communications
with the device connected to the Master port. When Auto Select mode is
enabled through the setup software, the 232BSS4 passes data automatically
from the Slaves to the Master.
Each Slave port is buffered until the Master is available, then sent in
turn. At any time, the Master can reply to the Slaves using the Send to
Specific Ports command, or override the automatic switching by selecting a
specific port for both transmit and receive.
When the Master device releases the Slave through the Turn Off all
ports command, the automatic switching resumes. The 232BSS4 will revert
back to the Slave port that was sending data before the Master took over or
to the next sequential Slave port with data in its buffer. For a full
description of the 232BSS4 commands, refer to the previous section,
“Smart Switch Only Mode.”
Options
Initial Connections:
Upon power-up, the 232BSS4 can be initialized to allow the Master
to send data to any of the Slave ports without any commands sent. The
Master can also be set to broadcast to any or all of the Slave ports on
power-up. This allows the switch to be used to add devices to an
existing COM port without any software programming. The port
initialization is configured through the setup software.
Timeouts:
When multiple Slave devices are sending data to the Master port at
the same time, the 232BSS4 must determine when to stop sending from
one Slave port and switch to the next. Two parameters are required to
be entered in the setup software for Auto Select mode. The Port Time
and Inactivity Time tell the 232BSS4 how much time to spend on each
port, and how long a port must be inactive before switching to the next
port.
Port Time:
Setting the Port Time for a value other than zero configures the
Master device to receive data from a single port only for the length of
time specified during setup. Times are set in milliseconds and can be
anywhere in the range of 0 to 65,000 (65 seconds). A value of zero for
the Port Time would give the transmitting Slave port access to the
Master until an Inactivity Timeout was reached or until a specific Turn
Off command was sent from the Master device.

Documentation Number 232BSS4-0812m 15
&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
When the specified Port Time has elapsed, the 232BSS4 checks in
sequence for other Slave ports with buffered data and switches to them.
If no other Slave ports need access to the Master, the current Slave port
will again be connected until another Port Time has elapsed.
Inactivity Time:
The Inactivity Timer tracks how long a Slave port has been idle. The
Inactivity Time is reset any time data is received on the connected Slave
port or sent out the Master Port. This way, if the Master port is slower
than the connected Slave port, the Slave port is not considered inactive
while waiting for the Master to catch up.
Inactivity Time is set through the setup software. Times are set in
milliseconds and can be anywhere in the range of 0 to 65,000 (65
seconds). A value of zero for the Inactivity Time would give the
transmitting Slave port access to the Master until a Port Timeout was
reached or until a specific Turn Off command was sent from the Master
device.
Port and Inactivity Time Setup Tips:
Normally, the Inactivity Time should be set lower than the Port
Time. Setting a zero for either value allows the other to have full control
of port switching. Setting a value of zero for both timeouts keeps the
Slave port connected until explicitly turned off by the Master device
through the Turn Off all ports command.
Slave Preamble:
Each Slave can be programmed to transmit a preamble to the
Master device when the Slave becomes connected. This tells the Master
device which new Slave is sending data. The preamble is set in the
setup software and can be any character sequence up to four characters
long. The preamble is sent to the Master device whenever a port is
selected through commands or when the port will be sending data to the
Master device because of an automatic switch.

16 Documentation Number 232BSS4-0812m
B&B Electronics Mfg Co Inc –707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] –www.bb-elec.com
B&B Electronics –Westlink Commercial Park –Oranmore, Galway, Ireland –Ph [phone] –Fax [phone] –www.bb-europe.com
Using the 232BSS4 as a Buffered Splitter/Combiner
The Auto Select and Initial Connection features of the 232BSS4
can be used to effectively create a data splitter. Data from the Master device
can be shared with multiple Slave devices. Any data coming from the
Slaves is buffered so that no data is lost. If the Slave devices already
include an address or identifier, no software changes are required.
Figure 2.1 shows a typical configuration allowing several serial
terminals access to the same host.
Terminal / HMI
CPU / Controller
Terminal / HMI
Terminal / HMI
Terminal / HMI
Port A Port B Port C Port D
MASTER PORT
232BSS4
+12 VDC
POWER
BB
&
electronics
MANUFACTURING COMPANY
www.bb-elec.com Ottawa, IL 61350 USA
Figure 2.1. Multiple Terminals to a Host Controller
To configure the 232BSS4 as a four port splitter/combiner:
Set up the ports on the 232BSS4 to match the data format of the
connected devices. If the Slave devices stream data, the Master port
should be set to a higher baud rate than the slaves.
Set the switches to turn on the Auto Select feature.
Set the Port Timer to 0. If the Slave devices stream data, the Time
per Port may have to be set to a non-zero value.
Set the Inactivity Timer on all of the switches to somewhere
between 20 and 500 milliseconds, depending on the space
between data packets and the response time required to
each connected device.
Set the Initial Connections for all ports to receive from the
Master on start up.