B&B Electronics 232XSSD4 User manual

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B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
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Expandable Smart Switch
Model 232XSSD4
Document No. 232XSSD43800
This product designed and manufactured in Ottawa, Illinois USA
of domestic and imported parts by
International Headquarters
B&B Electronics Mfg. Co. Inc. USA
707 Dayton Road - P.O. Box 1040 -- Ottawa, IL 61350
Phone [phone]
General Fax [phone] -- Sales Fax [phone]
Technical Support Fax [phone]
Internet:
www.bb-elec.com
[e-mail]
[e-mail]
European Headquarters
B&B Electronics Ltd.
Westlink Commercial Park, Oranmore, Co. Galway, Ireland
Phone: [phone] -- Fax: [phone]
Internet:
www.bb-europe.com
1997 B&B Electronics -- Revised October 2000

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TABLE OF CONTENTS
CHAPTER 1: HARDWARE...............................................................1
INTRODUCTION .......................................................................................1
SPECIFICATIONS......................................................................................2
CHECKLIST..............................................................................................3
SERIAL DATA CONFIGURATION...............................................................3
PORT CONFIGURATION............................................................................4
Master Port.......................................................................................4
RS-232 Configuration ............................................................................9
RS-422/485 Slave Port Option...........................................................10
RS-422/ RS-485 Mode............................................................................11
PORT EXPANSION BUS ..........................................................................13
SMART SWITCH OPERATION..................................................................13
Smart Switch Mode.......................................................................13
Three Character Command String.....................................................13
Four Character Command String.......................................................15
Programming the User Defined Character .......................................16
Smart Switch/Port Combiner Mode.............................................17
BINARY FILE TRANSFER .......................................................................18
PORT SELECT TEST...............................................................................18
CHAPTER 2: SOFTWARE.............................................................19
INTRODUCTION .....................................................................................19
WINDOWS SELECTOR PROGRAM INSTALLATION/INSTRUCTIONS...........19
SMART SWITCH SETUP..........................................................................20
DEFAULT VALUES.................................................................................20
SELECTING PORTS.................................................................................21
PARAMETERS........................................................................................21
UNINSTALLING WINDOWS SMART SWITCH SELECTOR PROGRAM .........21
DOS TSR INSTALLATION AND INSTRUCTIONS......................................21
Parameters.....................................................................................24
Default Values................................................................................26
Help Screen....................................................................................26
Selecting Ports...............................................................................26
Hot Key Method.............................................................................27
Command Line Method ................................................................27
Uninstalling the TSR .....................................................................28

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APPENDIX A: ACSII CHARACTER CODES............................A-1
APPENDIX B: CABLE CHARTS.................................................B-1
CHART 1. IBM PC DB25 CONNECTOR TO MASTER PORT.................B-1
CHART 2. IBM PC DB9 CONNECTOR TO MASTER PORT...................B-1
CHART 3. MODEM DB25 CONNECTOR TO MASTER PORT .................B-2
CHART 4. DCE DEVICE W/DB25 CONNECTOR TO PORTS A - H
(DTE) ......................................................................................B-2
CHART 5. IBM PC DB25 CONNECTOR TO PORTS A - H (DTE) ........B-3
CHART 6. IBM PC DB9 CONNECTOR TO PORTS A - H (DTE) ..........B-3
CHART 7. IBM PC DB25 CONNECTOR TO PORTS A - H (DTE).........B-4
CHART 8. IBM PC DB9 CONNECTOR TO PORTS A - H (DTE) ..........B-4
CHART 9. RS-422/485 4-WIRE DEVICE TO PORT (A - H)
CONFIGURED AS AN RS-422 /485 PORT...................................B-5
CHART 10. RS-485 2-WIRE DEVICE TO PORT (A - H) CONFIGURED
AS AN RS-485 PORT...............................................................B-5

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Chapter 1: HARDWARE
Introduction
The RS-232 Eight Port Expandable Smart Switch (232XSSD4)
allows one RS-232 host device to connect to eight asynchronous
serial devices. Refer to Figure 1. Four RS-232 ports and four RS-
232 or RS-485 (two or four wire, send data contol) are standard on
the 232XSSD4, depending on the pins you use. Other options and
additional RS-422/485 ports are available by contacting B&B
technical support. The 232XSSD4 can be easily expanded to add
up to sixty additional ports for a total of sixty-eight ports by using the
Model 232PE Port Expander. Ports configured as RS-232 support
signals TD, RD, RTS, CTS, DTR, and DSR or CD. Refer to Figure
5. Ports configured as RS-422/485 support signals TD and RD only.
Refer to Figure 6.
The Master port is DTE or DCE configurable. RS-232 ports "A"
through "H" are configured as DTE ports. The 232XSSD4 will switch
with baud rates from 300 to 38,400 bps, 7 or 8 data bits, even, odd
or no parity, and 1 or 2 stop bits. After the switch is made the
232XSSD4 is transparent to data flow.
There are nine red indicator LED's on the front of the
232XSSD4. Eight LED's represent ports "A" through "H" and
indicate the selected port. The ninth LED is the power on indicator.
Ten connectors are located on the back of the 232XSSD4, a twenty
pin expansion bus connector, a DB-25S female Master port
connector, and eight DB-25P male connectors for ports "A" through
"H". Refer to “Front View” diagram.
Port selection is accomplished by sending a programmable
control string to the "Master" port of the Expandable Smart Switch.
This control string consists of a user-defined character, address
character, and port character. When the 232XSSD4 receive the
control string the "Master" port will be connected to the designated
port. There is no delay through the 232XSSD4 and the data is not
buffered. When the 232XSSD4 is set to Smart Switch Mode Port "A"
will be selected at power up.
The eight ports on the 232XSSD4 can also be used as a smart
switch/port combiner. In addition to using the Master Port for port
selection, any of the eight ports can select the Master Port by
asserting their CTS line. This function is enabled by setting a switch
inside the 232XSSD4.

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Specifications
Model: 232XSSD4
Size: 10.1"w x 7.5"d x 3.3"h
Power: 120VAC 60hz 16w
Connectors: Master - DB-25 female (RS-232 or RS-422)
Slave - DB-25 male (RS-232 or RS-422/485)
Switching Baud Rate: from 300 to 38.4 Kbps
Baud Rate: Any baud rate up to 115.2 Kbps
Front View
Rear View

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Figure 1. Simplified Functional Diagram
NOTE: This diagram illustrates only the transmit data (TD) signal.
Checklist
The following equipment should be in the shipping carton:
1. Expandable Smart Switch
2. Instruction Manual
3. (2) 3 1/2" disks
If any of the items above are damaged or missing contact the
shipper immediately.
Serial Data Configuration
In order for the host device, which is connected to the Master
Port of the Smart Switch, to select a port, the Smart Switch must be
set to match the host's communication format. This is accomplished
by setting an eight position DIP switch labeled "SW1" located inside
the Smart Switch. Refer to Figure 2. Switch positions 1 through 4
select the baud rate. Switch position 5 selects 7 or 8 data bits.
Refer to Table 1. The remaining switch positions will be discussed
later. Always power down the Smart Switch before changing switch
settings.
Expansion
Port Combiner
Control Lines
Bus
Microcontroller
Master Port
TD
UART
Port ETD
Port HTD
CTS
CTS
Port H
Port A
TD
TDPort G Port F
Switch
Control
Port BTD
TD
TDPort D Port C
Ports "A-H"
TDPort A

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Port Configuration
The 232XSSD4 has a Master port and eight selectable ports
labeled "A" through "H". Refer to “Rear View”. The Master port
should be connected to the RS-232 device that will be selecting the
ports. Ports "A - H” connect to the RS-232 or RS-422/485 devices
that will communicate with the Master port device.
Master Port
The Master port can be configured by the user as a DCE or a
DTE port. In order to determine the proper Master port configuration
of the 232XSSD4 it is necessary to have a basic understanding of
the terms DCE and DTE. RS-232 was designed, using DB-25
connectors, for connecting a DTE (Data Terminal Equipment) device
to a DCE (Data Communication Equipment) device. Each device
will have inputs on pins that correspond to outputs on the same pins
of the other device. For example, a DTE device transmits data out
on pin 2 and a DCE device receives data in on pin 2. IBM PC's are
DTE devices, modems are DCE devices. The Master port is
shipped configured as a DCE port.
Table 1. Communication & Configuration Switch
DIP Switch 1
1 2 3 4 5 6 7 8 Setting
0000XXXX300 Baud
1000XXXX600 Baud
0100XXXX1200 Baud
1100XXXX2400 Baud
0010XXXX4800 Baud
1010XXXX9600 Baud *
0110XXXX19.2KBaud
1110XXXX38.4KBaud
XXXX0XXX8DataBits*
XXXX1XXX7DataBits
XXXXX0XXSmartSwitchMode *
XXXXX1XXSmartSwitchand
Port Combiner Mode
XXXXXX0X3Char.Command *
XXXXXX1X4Char.Command
XXXXXXX0PortSelectTestOff*
XXXXXXX1PortSelectTestOn
0 = OFF 1 = ON X = DON'T CARE
* = FACTORY DEFAULT

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Figure 2. Printed Circuit Board Outline

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Figure 3. Master Port DCE/DTE Jumpers
Figure 4. PC Board Options for RS-485
If an IBM PC (DTE device) is connected to the 232XSSD4
Master port, the Master port should be configured as a DCE port. If
a modem (DCE device) is connected to the Master port, it should be
configured as a DTE port. Refer to cable charts in Appendix B.
The Master port is configured as either a DCE port or a DTE
port by moving jumpers JP1: 1 through JP1: 7. JP1 is located inside
the Smart Switch. Refer to Figures 2 & 3. To configure the Master
port as a DCE port, jumpers JP1: 1 through JP1: 7 must be moved
to the DCE position. Refer to Table 2. To configure the Master port
as a DTE port, jumpers JP1: 1 through JP1: 7 must be moved to the
DTE position. Refer to Table 3.

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Important: All jumpers must be in the same position, either DCE or
DTE positions. Do not mix positions! Refer to Figure 3 which shows
the Master port configured as a DCE port.
CAUTION: Always power down the Smart Switch before removing
its cover.
Table 2. DCE MASTER PORT CHART
Pin # Signal Description
Signal
Direction of
DCE Master
Port
2TD Transmit Data Input
3RD Receive Data Output
4RTS Request to Send Input
5CTS Clear to Send Output
6* DSR Data Set Ready Output
7SG Signal Ground <------>
8* CD Carrier Detect Output
20 DTR Data Term Ready Input
14** TD (B) Transmit + Output
15** TD (A) Transmit - Output
16** RD (B) Receive + Input
17** RD (A) Receive - Input
* Pins 6 & 8 are tied together inside the 232XSSD4 and
share the same output. Refer to Figure 5.
** 422 master port option.

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Table 3. DTE MASTER PORT CHART
Pin # Signal Description
Signal
Direction of
DTE Master
Port
2TD Transmit Data Output
3RD Receive Data Input
4RTS Request to Send Output
5CTS Clear to Send Input
6* DSR Data Set Ready Input
7SG Signal Ground <------>
8* CD Carrier Detect Input
20 DTR Data Term Ready Output
14** TD (B) Transmit + Output
15** TD (A) Transmit - Output
16** RD (B) Receive + Input
17** RD (A) Receive - Input
* Pins 6 & 8 are tied together inside the 232XSSD4 and
share the same input. Refer to Figure 5.
** 422 master port option only

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The 232XSSD4 has eight ports labeled "A - H". Refer to “Rear
View”. Any of these ports can be manufactured to meet either RS-
232 or RS-422/485 electrical characteristics. The 232XSSD4 comes
standard with four RS-232 ports and four ports that are RS-232 or
RS-485 depending on the pins that you use.
RS-232 Configuration
All eight RS-232 slave ports will be wired as DTE ports. Refer to
Table 4 for pin out, signal name, and signal direction information.
Also, refer to Figure 5 for a simplified schematic showing the
relationship between the Master port and any RS-232 port "A-H".
Refer to Appendix B for cable charts.
Table 4. DTE PORTS A - H
Pin # Signal Description
RS-232
Signal
Direction of
DTE Ports A
through H
2 TD Transmit Data Output
3 RD Receive Data Input
4 RTS Request to Send Output
5 CTS Clear to Send Input
6* DSR Data Set Ready Input
7 SG Signal Ground <------>
8* CD Carrier Detect Input
20 DTR Data Term Ready Output
14** TD(B) Transmit (+) Output
15** TD(A) Transmit (-) Output
16** RD(B) Receive (+) Input
17** RD(A) Receive (-) Input
*Pins 6 & 8 are tied together inside the 232XSSD4 and share the
same input. Refer to Figure 5.
** RS-422/485 option if installed

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Figure 5. Simplified RS-232 Schematic
RS-422/485 Slave Port Option
The RS-232 transmit and receive data signals on the Master
port will be converted to balanced, full-duplex RS-422 or half-duplex
RS-485 signals with this option. The 232XSSD4 comes standard
with four RS-485 (2 or 4-wire) slave ports. Refer to Appendix B for
cable charts.
Table 5. RS-422/485 PORTS A - H
Pin # Signal Description
RS-422/485
Signal
Direction of
Ports A - H
15 TD(A) Transmit Data (-) Output
14 TD(B) Transmit Data (+) Output
7SG Signal Ground <------>
17 RD(A) Receive Data (-) Input
16 RD(B) Receive Data (+) Input

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When a port has this option, additional circuitry will be mounted
to the main board. The standard 232XSSD4 comes with the RS-485
option on four ports (Port A-D). Use Figure 2 to locate its position.
Refer to Table 5 for pin-out, signal name, and signal direction
information. Also, refer to Figure 6 for a simplified schematic
showing the relationship between the Master port and a port
configured with the RS-422/485 option.
NOTE: This option only supports transmit and receive data signals
(TD & RD) from the Master port.
RS-422/ RS-485 Mode
The model 232XSSD4 comes standard with an automatic send
data (SD) control of the RS-485 driver. SD control automatically
enables the RS-485 driver by sensing the leading edge of the first
character transmitted from the device connected to the Master port.
After the last character transmits, the send data timer circuit waits
one character time (about 1 millisecond at 9600 baud) before
disabling the RS-485 driver.
Figure 6. Simplified RS-422/485 Schematic

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There are two components located in the port B circuit area on
the main printed circuit board, a resistor (R75) and a capacitor (C4),
that are part of the send data control circuit. These components are
factory selected for 9600 baud, which allows the send data control to
operate at 9600 baud or higher. With these two components the
RS-485 driver will be disabled approximately 1 millisecond after the
last character has been sent. To change to a baud rate lower than
9600 baud, or to configure the send data control to match a specific
baud rate, change R75 and C4 to the value specified in Table 6.
Use Figure 3 to locate R75 and C4. Note that these timing
components are not used when the handshake control method is
selected.
To configure a port for RS-485 two-wire mode, both jumpers
must be placed in the two-wire "2" position for the corresponding
port Refer to Figure 4 for these jumper locations. The TD (A) and
RD (A) lines need to be connected together; also the TD (B) and RD
(B) lines need to be connected to each other. Giving you a Data (A)
line and a Data (B) line. “A” being “+” and “B” being “-“.
Handshake control (RTS) requires that the software use a
handshake signal to enable/disable the RS-485 driver. The
handshake signal RTS (pin 4) is used when the Master port is
configured as a DCE port and CTS (pin 5) is used when the Master
port is configured as a DTE port. If the RTS option is needed,
contact B&B Technical Support for details.
Table 6. Component Values For Send Data Timing
Baud
Rate Time (ms) Resistor Value R75 (ohms) Capacitor Value C4(microfarads)
300 33.3 330K .1
600 16.6 160K .1
1200 8.33 820K 0.01
2400 4.16 430K 0.01
4800 2.08 200K 0.01
9600 1.04 100K 0.01
19200 0.520 56K 0.01
38400 0.260 27K 0.01
56700 0.176 16K 0.01
115200 0.0868 8.2K 0.01

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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.

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Example 1: To turn on port E of the 232XSSD4 (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)
Example 2: To turn on port B located at port expander (232PE)
address ten with ASCII STX (2 decimal) character set
as the user defined character.
Send to the Master Port: STX A B
(2 65 66 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.
To turn any selected port off, the first and second character of
the command control string must be the user-defined character.
The third character must be the ASCII EOT character (decimal 4).
Example 3: To turn off all ports, with ASCII STX (decimal 2) set as
the user defined character.
Send to the Master Port: STX STX EOT
(2 2 4 decimal)
It is recommended that the user-defined character be a non-
printable character. The turn off command will then consist of three
characters that will not show up on the current port device.
If you were writing a program in GWBASIC to select port E of
the 232XSSD4 (address zero) you would form a string like this:
SW0E$ = CHR$(2) + "0" + "E"
You could then send SW0E$ to select port E. Similar strings could
be used for turning on the other ports. To turn off the ports the
string might look like this:
TOFF$ = CHR$(2) + CHR$(2) + CHR$(4)
NOTE: There is no delay through Smart Switch; data is not buffered.

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Four Character Command String
The four-character command adds additional security to port
selection. The only difference between the four-character command
and the three-character command is the addition of the ASCII
ESCape character in front of the three-character command.
The first character is the ASCII ESC character (decimal 27).
The second character is user-defined character. The third character
is the desired port address. The fourth character is the ASCII upper
case letter of the desired port. Refer to the "Three Character
Command String" section for more information regarding the last
three characters.
Example 1: To turn on port E of the 232XSSD4 (address zero) with
ASCII STX set as the user defined character.
Send to Master port: ESC STX 0 E
(27 2 48 69 decimal)
Example 2: To turn on port B located at port expander (232PE)
address ten with ASCII STX set as the user defined
character.
Send to Master Port: ESC STX A B
(27 2 65 66 decimal)
The turn off string also adds the ASCII ESC character to the
front of the three-character turn off string.
The first character is the ASCII ESC character. The second and
third character of the command control string is the user-defined
character. The fourth character is the ASCII EOT character
(decimal 4).
Example 3: To turn off all ports and the user defined character is
ASCII STX (decimal 2).
Send to Master Port: ESC STX STX EOT
(27 2 2 4 decimal)
It is recommended that the user-defined character be a non-
printable character. The turn off command will then consist of four
characters that will not show up on the current port device.

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If you were writing a program in GWBASIC to select port E of
the 232XSSD4 (address zero) you would form a string like this:
SW0E$ = CHR$(27) + CHR$(2) + "0" + "E"
You could then send SW0E$ to select port E. Similar strings could
be used for turning on the other ports. To turn off the ports the
string might look like this:
TOFF$ = CHR$(27) + CHR$(2) + CHR$(2) + CHR$(4)
NOTE: There is no delay through the Smart Switch and the
data is not buffered.
Programming the User Defined Character
The user-defined character comes programmed as the ASCII
STX character (decimal 2). You can change this to any 8-bit
character you wish by reprogramming DIP switch 2 (SW2). SW2 is
located on the printed circuit board inside the 232XSSD4. Refer to
Figure 2. SW2 is an eight-position switch with each position equal to
a certain weight. Refer to Table 4. It is recommended that a non-
printable character be defined.
For example, if you wish to use the ASCII NAK character as the
user defined character, which has a decimal value of 21, you would
turn on switches 1, 3, and 5 (1 + 4 + 16 = 21). Caution should be
used when selecting the user defined character, so that by itself, or
with the ESC character in front of it (4-character command), or with
the character following it, it is not a valid command to any of the
devices connected to the ports. For instance, on some printers ESC
@ is the reset command. If you tried to use the @ symbol (decimal
64) for the user defined character you could reset your printer every
Table 4. SW2 WEIGHT CHART
DIP Switch 2 WEIGHT
11
22
34
48
516
632
764
8 128

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time the command control string is sent. Note also, that if your
communication configuration is set for 7 data bits you cannot use the
eighth position of SW2. For a list of the ASCII character codes and
their decimal values refer to Appendix A.
Smart Switch/Port Combiner Mode
This mode allows the CTS lines of ports A - H of the 232XSSD4
to select the Master port. It also allows selection from the Master
port via the command control string described in the Smart Switch
Mode section. Position 6 of DIP switch 1 (SW1) must be in the ON
position to enable this mode. Refer to Figure 2. When all ports are
off and the CTS line (pin 5) goes high on any of the eight ports, a
connection is established from that port to the Master port. This
works on a first-come-first-serve basis and only for RS-232
configured ports. At power up in this mode there is no port selected.
For example, if port A of the 232XSSD4 wanted to established a
connection to the Master port, port A would raise its CTS line (pin 5)
high. The 232XSSD4 would recognize this as a prompt for
connection to the Master port. The connection would be dropped as
soon as the CTS line on port A was lowered. At that time any of the
other RS-232 ports on the 232XSSD4 can raise their CTS line to
establish connection. If port A is connected to the Master port and
any of the other RS-232 ports on the 232XSSD4 raises their CTS
line, the data sent to the 232XSSD4 from those ports would be lost.
The 232XSSD4 does not have buffering.
Note that when a port is selected via the Master port, the CTS
lines will be ignored until the Smart Switch receives the turn off
command from the Master port. When a CTS line selects the
Master port, all commands will be ignored until CTS goes low.
A typical application would be to tie CTS & RTS together on the
Master port. So when CTS on a port is raised, RTS on that port also
goes high establishing a connection for your hardware. Note that
RTS will be low until connection to the Master port has been
completed. The other ports will be held off because TD, RTS, and
DTR will be low. After CTS goes low, the 232XSSD4 will scan the
CTS lines starting with the next port. When there are no ports
selected Port A will have first priority, port B second and so on.
NOTE: The port combiner function is not available on the Port
Expander units.