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Chapter 3: Smart Switch Operation
Smart Switch mode is selected when jumper "JP6-B" is ON
(installed). In Smart Switch mode, the 232XS5 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
232XS5 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 ASCII character STX (decimal 2). The third
character should be the ASCII upper case letters "A", "B", "C", "D"
or "E" (decimal 65, 66, 67, 68 or 69 respectively) to select those
ports. To turn off the selected port the third character should be the
ASCII EOT character (decimal 4). The ASCII characters and their
equivalent decimal values are listed in Appendix A.
Example:
To turn on port B you would send the three ASCII characters:
ESC STX B
If you were writing a program in BASIC to control the 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 Smart Switch and the
data is not buffered.
232XS5-1005 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
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 eight-
position switch with each position equal to a certain weight. Refer to
"Setup" for instructions on removing the cover to access "SW2".
Table 6 shows the weight chart for "SW2".
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.
Note also that 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 Smart Switch to transfer binary
files without the concern of it accidentally disconnecting, is to set the
file transfer at a baud rate different from the baud rate of the Smart
Switch. When transferring files at a different baud rate, the Smart
Switch will stay connected from the last preamble code.
8
7
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
Programmable Character Setting
Table 6.
Dipswitch SW2*
1
2
3
4
5
6
7
8
*Factory Default -- ASCII "STX" character
(decimal 2), SW2 position 2 is only one ON.
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
WEIGHT
1
2
4
8
16
32
64
128
232XS5-1005 Manual
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