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MODULAR SMART SWITCH
7. Serial Port Control Utility
The control software allows serial ports on IBM compatible PCs to be run at
the high baud rates supported by the Modular Smart Switch. The utility can
be used to control COM1 or COM2 and supports a wide range of protocols.
The time-saving advantages of running serial ports at higher baud rates can
be quite dramatic, and the control software makes sure that the correct
protocol is used regardless of the settings on the application program.
Although DOS will normally only support baud rates up to 9600, most PCs
are capable of running at much higher speeds of 19,200, 38,400, or 57,600
baud. A number of high-baud-rate utilities are available that act like the
DOS MODE command. But these can be of little practical use, since many
application programs change the baud rate and protocol when they run.
The control software overcomes this problem by preventing application
programs from changing the baud rate or protocol of the serial port being
controlled. This has two major advantages. First, the user does not need to
worry about setting the baud rate and protocol in the application program.
Second, high baud rates can be used for plotting from packages that would
normally only support lower baud rates.
To run the control software, copy the program ADMODE.COM from
the utility disk to a suitable directory on your PC. At the DOS prompt,
type a command in the following format.
ADMODE COMn: baud, parity, databits, stopbits
You only need to include a parameter after baud if it needs to be changed
from the default values shown in Table 7-1. The minimum command syntax
is:
ADMODE COMn: baud
Example
To set serial port 1 (COM1) to 38400 baud, 8 data bits, 1 stop bit,
and no parity, use the following command.
ADMODE COM1:38400,N,8,1 <enter>
High-Baud-Rate Limitations
In practice, almost all modern PCs will support baud rates of 38,400.
However, a number of PCs that we tested were not able to support baud rates
of 57,600 because of the design of their serial ports. If you have problems
with particular PCs, try reducing the baud rate.
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MODULAR SMART SWITCH
6.10.2 C
HANGING THE
T
IMEOUT
The timeout period can be varied from the default of 16 seconds to any value
between 1 and 255 seconds, or it can be permanently off. To do so, select
the TIMEOUT option and type the required value into the entry box. Press
<enter> to return to the options menu. To return to the default value of
16 seconds, press <escape>.
6.10.3 S
ELECTING A
PC P
ORT
If the correct PC port is not shown on the main menu (G in Figure
6-1), then use the PC PORT option to select this. Highlight the PC PORT
option and type <enter>. Use the <up> and <down> cursor keys to select
the desired port (highlighted) and then press <enter>. The PC port you
have selected will now be displayed.
NOTE
The control software defines the routing from the selected port on your
PC—it does not set the port that your software will use for output.
