Digital Loggers SS20 User manual

20-Port
Serial Switch
User’s Guide

Product F
Product FProduct F
Product Features
eatureseatures
eatures
• 20 ports of relay isolated serial interfaces.
• On-board µP with EEPROM.
• Manual or batch-file operation via simple te t menus.
• Ability to broadcast through multiple ports simultaneously.
• Support for any baud rate or data format after connection.
Device R
Device RDevice R
Device Requirements
equirementsequirements
equirements
• Any three-wire RS-232 source and targets may be
connected.
• Baud rates of 9600, 19,200, 38400, and 115,200 are
supported for communications with the menu system. Any
baud rate (ie. 110 baud to 2Mbaud) may be used to
communicate with attached devices
.
Capabilities and Limitation
Capabilities and LimitationCapabilities and Limitation
Capabilities and Limitations
ss
s
A crosspoint data switch provides a link from one host device
(such as a controlling PC or modem) to several attached devices
(such as routers, servers, cable receivers, radios, or sensors). Use
the switch to control several serial devices from a single port.
The switch provides a cost-effective alternative to multi-port
serial cards when you only need to communicate with one device
at a time.
The switch can broadcast data to multiple devices
simultaneously. It receives from only one device at a time.
There is no buffering or memory within a crosspoint switch.
Characters transmitted when a port is turned off are ignored.
Only data on pins 2 & 3 of the DB-9 is switched. Handshaking
isn’t switched.

Hardware
Hardware Hardware
Hardware Setup
SetupSetup
Setup
A 5V wall adapter provides regulated DC power to the switch.
The ma imum current drain of 600mA occurs when all ports are
switched on. Normal power consumption is under 1W.
Two types of ports are provided, console and device. The
control (console) port can connect with a PC via a straight-
through cable, or to a modem via a crossover cable. The control
port pinout is:
Pin 2 = RX Receive Data (data from devices A-T and
from the switch to control port)
Pin 3 = TX Send Data (data to switch procesor and to
devices
A-T from the control port)
Pin 5 = Ground
Handshaking lines are strapped for no flow control (always on).
Pins 1, 6 and 4 are strapped. Pins 7 & 8 are also strapped.
Device ports labeled A-T connect up to 20 managed devices.
Device port pinout is:
Pin 2 = TX Transmit Data (data to devices A-T)
Pin 3 = RX Receive Data (data from devices)
Pin 5 = Ground
Handshaking lines are strapped for no flow control (always on).
Pins 1, 6 and 4 are strapped. Pins 7 & 8 are also strapped.
Note that data from the control device flows is from pin 3 of the
control port to pin 2 of the device ports A-T. Returning data
from the A-T device ports pin 3 flows back to pin 2 of the
control port. The switch itself is essentially a “crossover”
“none”.
w control to
N,8,1 when first connecting to the switch. Set flo
t at 9600,
device. Connect a PC or terminal to the control por

Menu Operation
Menu OperationMenu Operation
Menu Operation
Press ~ (tilde), wait at least ½ a second, and press ~ again to
enter the menu. Once the menu is entered, communication with
attached devices is disabled. The following message appears:
Serial Switch Unit Name: Serial Switch
Enter Command (? for help):
Valid commands are:
A-T
Toggle the specified port
This command enables (connect) or disables
(disconnect) a single device port 1-20 (1=A,
2=B…20=T). Port switching is performed
after e iting the menu with the “X” or “ESC”.
Z
Enable all 20 ports for broadcast
This enables simultaneous transmission from
the control port to all attached devices.
This is useful when configuring a number of
identical devices. Port switching is performed
after e iting the menu with the “X” or “ESC”.
W
Disable all ports.
Any enabled ports will be disabled after
e iting the menu with the “X” or “ESC”.
U
Set baud rate.
Note that the baud rate of the switch may be
different than the baud rates of the attached
devices. This baud rate is used only by the
menus. You may transmit at any other baud
rate or send non standard bit streams to the
attached devices after switching. Baud rates
of 9600, 19,200, 38400, and 115,200 are
supported. All baud rates operate at 8 bits,
baud rates.
forget the setting, you’ll need to try all four
write down the baud rate you select. If you
no parity and no handshaking. Be sure to
volatile EEPROM.
characters and are saved immediately in non-
Router”. These settings are limited to 16
switch. For e ample, Port 1 might be “Cisco
It can be useful to label ports and label the
.
Change Unit or ort Name
Y
1y
Toggle dela
oggle the delay requirement between the attention characters.
T
off) of each port, along with the unit names.
This command displays the settings (on or
Show port settings
V
crosspoint relays are enabled.
be used to e it the menu at which time the
Either an ASCII “X” 0 58 or ESC 0 1B may
X or Esc Escape

Batch File Operation
Batch File OperationBatch File Operation
Batch File Operation
Manual and batch file control function and synta is identical.
There are three important considerations when using batch files:
1.
The switch doesn’t react instantly to commands. It
takes appro imately 1/20
th
of a second for the
crosspoint switch to complete a switching command.
To compensate for this, either use a delay command or
send a few null characters. Nulls are normally ignored
by RS-232 devices. At 9600 baud, 40 nulls are required.
Be sure to insert a delay between the ~ attention
characters to enable the switch. You can disable this
delay to simplify your batch file and speed up
switching. Do this only if you’re certain the two
attention characters will not be inadvertently sent in the
data stream.
2.
The e act synta of a command is important. For
e ample, “Echo ~>COM1” and “ECHO ~ >COM1”
opened as a stream I/O device using stdio:
details. Once a port is set up, a com port can be
Type mode /? in at command line prompt for full
stop 1" )
system( "mode com1: baud 9600 parity n data 8
command in a system() function call:
he mode
In Windows, you can configure a serial port using t
Pro rams
Pro ramsPro rams
Communicatin from Pro rams
Communicatin from Communicatin from
Communicatin from
transmit simultaneously to multiple ports.
ay
Again, only one port can “listen” at a time. You m
3.
output string.
the
strlen(str)) instead of fprintf() which will buffer
, str,
program, it’s sometimes desirable to use write(port
n a
0 20 after the ~ in the second e ample. From withi
er
are different. Windows will send the space charact
evfs.html
http://www.atnf.csiro.au/people/rgooch/linu /docs/d
For Linu serial communications, try:
-us/dnfiles/html/msdn_serial.asp
library/en
http://msdn.microsoft.com/library/default.asp?url=/
information on W32 serial communications, see:
For
simpler stdio function works for many applications.
ut the
comprehensive low level functions for serial I/O, b
s
You can also use C++ fstream I/O. The Win32 API ha
printf( menuresponse ) ;
/* you’re in to the menu, send commands next */
fgets( menuresponse, sizeof( response ), portfp ) ;
fprintf( portfp, "~" ) ; /*send second tilde */
Delay (500); /* wait 500ms */
fprintf( portfp, "~" ) ; /*send tilde */
FILE* portfp fopen( "com1:", "w+" ) ;
char menuresponse[128] ;

Alternate Attention Character
Alternate Attention CharacterAlternate Attention Character
Alternate Attention Character `
``
`
The default attention character is tilde ~ decimal 126, 0 7E
To select the alternate ` character decimal 96 0 60, move the
switch toward the center of the serial switch. You can use
different attention characters or baud rates to “daisy chain”
multiple switches in series.
Hayes Command Reference
Hayes Command ReferenceHayes Command Reference
Hayes Command Reference
These Hayes commands are commonly used with attached
modems. Check Wikipedia for a full list.
+++ (pause) Attention characters
ATDT 408 555 1212 Dials out to [phone]
AT A Answers incoming call
ATS0 1 Sets modem to answer after 1 ring
ATS37 8 Sets modem to 9600 baud
Telnet Option
Telnet OptionTelnet Option
Telnet Option
The Telnet option module adds Ethernet connectivity to the
control port. Visit www.digital-loggers.com/telnet.html or call
[phone] for more information. A pushbutton switch is
provided to reset the Telnet module to default IP setting. This
button has no effect if the Telnet module is not installed.

A
AA
Accessories
ccessoriesccessories
ccessories
DLI stocks RJ-45 to DB-9 and DB-
25 adapters, as well as cable. These
adapters allow you to insert pins in
any order, so you can create
crossover or straight-through cables easily. Flat phone-type satin
cord makes a clean installation, particularly with Cisco, Sun and
Dish Network equipment. Call [phone] for connectors
or cables.
Support
SupportSupport
Support
Please visit www.digital-loggers.com for manuals and
accessories. If we haven't answered your questions here, please
call [phone] or send an email to support@digital-
loggers.com. We'll be glad to help. Kudos, suggestions, gripes?
Send them all to [e-mail]