B&B Electronics 232MSS2 User Manual

Mini Smart Switch CE

Model 232MSS2

Documentation Number 232MSS2-0108

pn3662-rev006

This product designed and manufactured

of domestic and imported parts by

International Headquarters

B&B Electronics Mfg. Co. Inc.

707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350 USA

Phone [phone] -- General Fax [phone]

Home Page: www.bb-elec.com

Sales e-mail:

Technical Support e-mail:

Westlink Commercial Park, Oranmore, Co. Galway, Ireland

Technical Support e-mail:

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[e-mail] -- Fax [phone]

[e-mail] -- Fax [phone]

European Headquarters

B&B Electronics Ltd.

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Home Page: www.bb-europe.com

Sales e-mail:

 1995 B&B Electronics --- Revised January 2008

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TABLE OF CONTENTS

Chapter 1: INTRODUCTION ................................................ 1

Checklist ................................................................................ 2

Chapter 2: SETUP ................................................................ 3

Port Configuration ................................................................. 4

Serial Data Configuration ...................................................... 5

Smart Switch Operation ........................................................ 5

Programming the Second Character .................................... 7

Binary File Transfer ............................................................... 7

Smart Switch/Port Combiner Mode ....................................... 8

Specifications ...................................................................... 11

Chapter 3: SOFTWARE ..................................................... 13

Introduction .......................................................................... 13

Windows SSwitch ................................................................ 13

DOS SSTSR ........................................................................ 14

Parameters .......................................................................... 16

Default Values ..................................................................... 17

Help Screen ......................................................................... 17

Un-Install ............................................................................. 17

Selecting Ports .................................................................... 17

Hot Key Method ................................................................... 18

Command Line Method ....................................................... 19

APPENDIX A: ASCII Character Codes .......................... A-1

APPENDIX B: Cable Charts ............................................ B-1

Chart 1. IBM PC DB25 Connector to Master Port .............. B-2

Chart 2. IBM PC DB9 Connector to Master Port ................ B-2

Chart 3. Modem DB25 Connector to Master Port .............. B-3

Chart 4. IBM PC DB25 Connector to Ports A - D (DTE) .... B-3

Chart 5. IBM PC DB25 Connector to Ports A - D (DCE).... B-4

Chart 6. IBM PC DB9 Connector to Ports A - D (DTE) ...... B-4

Chart 7. IBM PC DB9 Connector to Ports A - D (DCE) ...... B-5

Chart 8. IBM PC DB25 Connector to Ports A - D (DCE).... B-5

Chart 9. IBM PC DB9 Connector to Ports A - D (DCE) ...... B-6

APPENDIX C: Declaration of Conformity ...................... C-1

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Chapter 1: INTRODUCTION

The RS-232 Four Port Mini Smart Switch/Port Combiner, Model
232MSS2, allows one RS-232 host device to connect to as many as
four RS-232 devices. The switch can be controlled in two different
ways. The first way is referred to as smart switch mode. In this
mode, the switch is controlled by sending a programmable preamble
code to the "Master" port of the 232MSS2. The other way the switch
can be controlled is referred to as port combiner mode. In port
combiner mode, a slave port can gain access to the master port by
asserting a handshake line. If none of the slave ports have their
handshake line asserted, the switch can be controlled using the
preamble code.
The master port can be configured as a DTE or DCE port by an
internal switch setting. If the master port is configured as a DTE port,
the four slave ports will become DCE ports. The 232MSS2 supports
the following signals: TD, RD, RTS, and CTS.
The 232MSS2 has an enhanced mode which offers special
timer features. The timer features can be used to prevent slave
devices from receiving preamble commands, inadvertently switching
from binary/graphic file transfers, and inactive slave devices from
holding control of the master port.
The 232MSS2 will work with baud rates from 1200 to 115,200
bps; 7 or 8 data bits; even, odd or no parity; and 1 or 2 stop bits
(7,N,1 is not allowed).

NOTE: The data format and rates mentioned are used to switch
the 232MSS2. The communication between the devices can use
any format or data rate.

There are four LED's on the 232MSS2 to indicate which port is
connected to the master port. The master port has a DB-25S female
connector and the slave ports have DB-9S female connectors. The
232MSS2 requires 12Vdc at 10ma. which is provided through a

2.5mm power jack.

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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 Mini Smart Switch

2. Instruction manual

3. Software media
If any of the items above are not in the shipping carton contact

the shipper immediately.

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Chapter 2: SETUP

The 232MSS2 is set up using an eight-position dipswitch. This
dipswitch is used to set the communication format, port config­uration, smart switch/port combiner mode and to enable/disable the
enhanced features. To change the settings on the switch, remove
the power from the unit, and remove the screws (4) from the bottom
of the 232MSS2. The dipswitch is located on the top of the PC board
(side with LEDs) and is labeled “SW1.” The other dipswitch, labeled
“SW2” is used to set the second character of the preamble. After the
switches have been set to match your requirements, you can put the
unit back together. NOTE: The end panel should be open end
towards the bottom of the PC board and the smooth side goes
toward the inside. Table 1 shows the settings for dipswitch “SW1”.

Table 1. Communication & Port Setup

Dipswitch SW1
1 2 3 4 5 6 7 8

0 0 0 X X X X X 1200 Baud
1 0 0 X X X X X 2400 Baud
0 1 0 X X X X X 4800 Baud
1 1 0 X X X X X 9600 Baud *
0 0 1 X X X X X 19.2K Baud
1 0 1 X X X X X 38.4K Baud
0 1 1 X X X X X 57.6K Baud
1 1 1 X X X X X 115.2K Baud
X X X 0 X X X X Enhanced Disabled *
X X X 1 X X X X Enhanced Enable
X X X X 0 X X X 8 Data Bits *
X X X X 1 X X X 7 Data Bits
X X X X X 0 X X Parity Disabled *
X X X X X 1 X X Parity Enabled
X X X X X X 0 X Smart Switch Mode*
X X X X X X 1 X Port Combiner Mode
X X X X X X X 0 DCE master port *
X X X X X X X 1 DTE master port

0 = OFF 1 = ON X = DON'T CARE
* = FACTORY DEFAULT

Setting

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Port Configuration

In order to determine the proper port configuration of the
232MSS2, 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 will transmit data out
on pin 2 (on a DB-25) and a DCE device will receive data in on pin 2
(on a DB-25). IBM PCs and serial printers are DTE devices,
modems are DCE devices.
If an IBM PC (DTE device) is going to be connected to the
232MSS2 master port, the master port should be configured as a
DCE port. If a modem (DCE device) is going to be connected to the
master port, it should be configured as a DTE port.
The master port can be configured as a DCE port (data received on
pin 2) or a DTE port (data received on pin 3) by setting dipswitch
“SW1”, position 8. To configure the master port as a DCE port, move
dipswitch “SW1”, position 8, to the "OFF" position. When the master
port is configured as a DCE port, ports A, B, C, & D will become
DTE ports (Refer to Table 2). To configure the master port as a DTE
port move dipswitch “SW1”, position 8, to the "ON" position. When
the master port is configured as a DTE port, ports A, B, C, & D will
become DCE ports (Refer to Table 3). Always power down the
smart switch when changing switch settings.

Table 2. DCE MASTER PORT CHART

Master Port

(DCE)

Pin# Direction Description Pin# Direction

2 Input Transmit Data (TD) 3 Output
3 Output Receive Data (RD) 2 Input
4 Input Request to Send (RTS) 7 Output
5 Output Clear to Send (CTS) 8 Input
7 <-------> Signal Ground (SG) 5 <----->

Signal

A,B,C & D Ports

(DTE)

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Table 3. DTE MASTER PORT CHART

Master Port

(DTE)

Signal

A,B,C & D Ports

(DCE)

Pin# Direction Description Pin# Direction

2 Output Transmit Data (TD) 3 Input
3 Input Receive Data (RD) 2 Output
4 Output Request to Send (RTS) 7 Input
5 Input Clear to Send (CTS) 8 Output
7 <-------> Signal Ground (SG) 5 <----->

The 232MSS2 supports the following RS-232 signals: TD, RD,
SG, RTS & CTS.
NOTE: Handshake lines DSR and DTR are tied together on
each connector and are not passed through to the master port. All
other lines are not connected.
The Mini Smart Switch selects port A as the default port at power
up.

Serial Data Configuration

In order for the host device that is connected to the master port
to select any of the four ports, the Mini Smart Switch must be set to
match the host's communication format. Dipswitch “SW1” is used to
select the communication format of the Mini Smart Switch. Switch
positions 1 through 3 select the baud rate. Switch position 5 selects
7 or 8 data bits. Switch position 6 determines if parity is enabled or
disabled.
NOTE: A data format of 7 data bits, no parity and one stop is
not allowed.
Switch position 8 selects the port configuration, see section titled
"Port Configuration". Refer to Table 1. Always power down the smart
switch when changing switch settings.

Smart Switch Operation

Smart Switch mode is selected when dipswitch “SW1” position 7
is “Off.” In Smart Switch mode, the 232MSS2 is constantly looking
for the three character preamble code by monitoring the data that is
being received on the master port from the host device. The
232MSS2 requires a three 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

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ASCII character STX (decimal 2). The third character should be the
ASCII upper case letters "A", "B", "C" or "D" (decimal 65, 66, 67, or
68 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 you would send:

ESC STX B

If you were writing a program in BASIC to control the Mini Smart
Switch you would form a string like this:

SWB$ = CHR$(27) + CHR$(2) + "B"

You could then send SWB$ to select port B. 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$(4)

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.
We recommend that you turn off the selected port before selecting
the next one. The turn off command consists of three characters that
are nonprinting (ESC STX EOT). If port A is selected and you send
the command to select port B, all three characters (ESC STX B) will
pass through the A port since it is still selected and the letter B will
show up on your port A device. For information on preventing
command codes from being received by slave devices, refer to the
Enhance Mode section.
NOTE: There is no delay through the Mini Smart Switch and
the data is not buffered.

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Programming the Second Character

The second character comes programmed as the ASCII STX
character (decimal 2). You can change this to any 8-bit character
you wish by reprogramming dipswitch “SW2”. “SW2” is an eight­position switch with each position equal to a certain weight. Refer to
“Setup” for instructions on removing the cover to access “SW2”.
Table 4 shows the weight chart for “SW2”.

Table 4.

Programmable Character Setting

Dipswitch SW2* WEIGHT

1 1
2 2
3 4
4 8
5 16
6 32
7 64
8 128

*Factory Default -- ASCII “STX” character

(decimal 2), SW2 position 2 is only one ON.

If you wish to use the letter "U" as the second character, which
has a decimal value of 85, you would turn on switches 1, 3, 5, and 7
(1 + 4 + 16 + 64 = 85). Caution should be used when selecting the
second character, so that by itself, or with the ESC character in front
of it, it is not a valid command to any of the devices on the port. For
instance, on some printers ESC @ is the reset command. If you
tried to use the @ symbol (decimal 64) for the second character you
could reset your printer every time the preamble code was sent.
Also, if your communication configuration is set for 7 data bits you
cannot use the eighth bit of SW2. For a list of the ASCII character
codes and their decimal values, refer to Appendix A.

Binary File Transfer

A simple method of using the Mini Smart Switch to transfer
binary files without the concern of it accidentally disconnecting, is to
set the file transfer at a different baud rate from the rate of the Mini
Smart Switch. When transferring files at a different baud rate, the
Mini Smart Switch will stay connected from the last preamble code.

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