Troubleshooting Windows for Disconnects
Testing the Line
You can determine whether your problem is related to a software conflict
or a line noise problem by using a dedicated data comminucations program
(i.e. Procomm, Quicklink, etc.) and logging into our shell.
If you are able to maintain a connection, then disconnects possibly
reflect some conflict between Trumpet Winsock (or other PPP dialler) and
your system. Try starting windows in the safe mode or check your
comm port settings.
If you are unable to maintain a connection you may be experiencing
line noise problems.
Choosing a Baud rate
To find the right baud rate for your external modem, at DOS type "MSD" to
enter Microsoft Diagnostics. Press "c" for Communications and you should
see a list of your comm ports.
Use this chart to check what type of UARTs you have.
8250 - Trumpet Winsock will not support Baud rates above 19200
16450 - Trumpet Winsock will not support Baud rates above 38400
16550 - Although speeds of 115200 are possible, Miscrosoft claims
that Windows 3.x does not support speeds above 57600.
Most internal modems are equivallent to com ports with 16550 UARTS.
For more information about your modem and baud rates, click here.
Modem Init Strings
A solid modem init string is very importent if you are experiencing
connection problems. Check your manual for a Hardware Handshaking
factory default, or click here for a list of manufacturer-recommended
strings by modem type.
Try adding S10=40 at the end of the recommended string to make it hang on
the line during loud line bursts. You can increase this number up to
255, although I would not recommend much above 100.
(This information is not necessary for Windows NT or 95, or Windows
It is VERY important to setup Windows 3.x properly in order to avoid comm
overruns (i.e., missing incoming data). Minimize problems by assuring
that the Windows SYSTEM.INI file, under the [386Enh] section, is properly
set up. First, make sure that the following two lines, if present, read:
Also, add the following lines to the [386Enh] section:
You may also wish to replace the default Windows COMM.DRV in SYSTEM.INI
with a third-party driver, if you have comm overrun problems that you
can't otherwise fix. You can get cybercom.zip.
Starting Windows in the 'safe' mode
- Windows 3.x: Exit Windows. Type: win /3 at the dos prompt.
- Windows 95: Restart your machine. When your screen says 'Starting Windows
95' press the F8 key. You should see a menu of options.
3 Safe mode - if you are using Trumpet Winsock.
4 Safe mode with network support - if you are using the Win95
28,800 bps modems require some special considerations.
Unless you have a 16550 UART or an internal 28.8K
modem, you can not set your baud rate higher than 19200 in Trumpet
Winsock. In this situation, we recommend that you turn off any data
compression (V.42bis or MNP 5). Check your modem manual (USR modems, for
example, use the &K0; command to disable data compression). Include this
command in your modem init string.
If you have a 16550 UART and an external modem, make sure your modem is
connected to the comm port that has the 16550 UART. If you have a choice,
either externally or internally, choose COM2. COM2 has a higher interrupt
priority than COM1. This is especially important if you have a serial
mouse, and have a slower system. Start with your Baud Rate in Trumpet
Winsock set to 57600 and make sure, if you are using Windows 3.x, that you
set up the system.ini file.
After Windows is set up correctly, be sure to use a Hardware Handshaking
modem init string for your modem, and include the S10=20 command. If this
doesn't help, lower your baud rate to 38400. If this doesn't help, lower
your baud rate to 19200, and be sure to disable data compression, and
again to 9600. If any of these low speeds work, this may reflect other
conflicts within your system. Try exiting windows, and restarting using
the safe mode, then start over with 57600. Also, check Line Noise for other
MAKE SURE you only have one copy of winsock.dll on your system. Having
multiple copies WILL cause problems, sometimes even when one is not in
your path statement.
Make sure your Trumpet setup values are set properly. MTU (the Maximum
Transmission Unit) is normally set to MSS (the Maximum data Segment Size)
plus 40 because the size of header added to the packet is usually 40 bytes
(20 bytes for TCP and 20 bytes for IP). RWIN stands for receive window,
and is a buffer your PC waits to fill before attending to other TCP/IP
transactions while you have a download in progress. RWIN needs to be large
enough to keep the pipe full for downloads, but not so large that other
threads experience delays due to latency. Most people will find that RWIN
values 4 times MSS is a good compromise. Try the following.
Trumpet Winsock SETUP (under FILE):
- MSS: 536
- MTU: 576
- RWIN: 2144
You may wish to try lower MTU values.