Configuring Your Modem: For Windows 3.x Users

What is a Modem?

A modem is a device your computer uses to send and receive electronic data through your phone line. It connects your computer to your phone line, giving you access to the internet and the World Wide Web. The modem may live inside your computer (internal modem) on a "modem card," or may be connected by serial cable outside your computer (external modem). Your telephone line plugs into the modem on one end, and into a telephone wall (RJ-11) jack on the other.

Your modem also plugs into one of your computer’s communications ports such as "COM1" or "COM2" (often labeled "serial 1" or "serial 2"). If your computer has only one serial port, it most likely is COM1; if it has two, one will be COM1 and one will be COM2. Computers using a serial mouse often will plug it into the "COM1" port (unless the computer is equipped with a special mouse port), leaving only the COM2 port for connecting a modem.

When you set up your computer, you must tell the operating system which "COM port" you are using for your telephone line, the type and speed of modem you are using, and other information about using the communications port (many software products can now do this for you).

Although the Windows 3.x operating system does not include any built-in capability for automatically detecting your brand of modem, the CNC Internet Access Kit's installation program comes equipped with a vast list of modem configurations and is usually capable of automatically setting one up for you.

You should need the following steps for configuring your modem ONLY if Concentric's installer had difficulty automatically detecting and configuring your modem for you.

Steps to Configure Your Modem and COM Ports

1. Make sure a telephone line connects your modem to your computer’s communications port (sometimes called a "serial port" or "IOIOI"), and that your modem is plugged into a standard phone jack.
2. Double-click the Windows 3.x Control Panel icon from inside the Main Group.
3. Double-click on the Ports icon.
4. Double-click the icon corresponding to the COM port you want to configure, or click once on it, then click on the "Settings" button. If you have two serial ports on your computer, you are generally safe selecting COM2.
5. Set the modem speed (baud rate) at 14,400 or higher (depending on the capabilities of your modem). Bear in mind that data compression permits data transfers at rates considerably higher than your modem speed. Some "28,800-baud" modems can transfer at speeds up to 115,200 baud, for instance.
6. Set the preferences for connecting to CNC at 8-N-1:
   8 Data bits
   No Parity
   1 Stop bit.
7. Set the flow control setting to "hardware" unless you know that your modem does not support this (in which case, set it to "Xon/Xoff").
8. The default settings revealed by clicking the "Advanced" button are preferred for most situations and should be changed by advanced users only if necessary.
9. To reinstall your modem selection you will need to run your dialer. To do this,
   1.  
   2. From your CNC window, double-click the "Concentric Network Dialer" icon.
   3. Click the "Properties" button.
   4. Click the Modem tab.
   5. Click on the "Change modem" button and select your modem from the list.
   6. If your modem does not appear on the list, first try the "Hayes compatible" setting. If this does not work, try the "Other Windows modem" setting.
   7. Click the OK button when you are done.
10. Make sure your modem and phone line are not in use by any other program.

Give Me Just the Settings

CNC’s Local Access Numbers operate at a maximum standard baud rate of 28,800, which, with data compression set, can exceed throughput speeds of 56,000, with occasional burst speeds up to 115,200 baud. Standard Modem Settings Are:

Baud Rate: 14,400 or higher
RTS/CTS Hardware Flow Control: Enabled (superior to XON/XOFF (software) control).
Data bits: 8
Stop bits: 1
Parity: N

Additional modem considerations:

• Your modem may not consistently connect at its rated baud rate. If the difference is small (such as connecting at 26,400 instead of 28,800 baud), this may be normal. Sometimes the actual data transmission rate is slowed down due to the connection grade or the physical type of connection you have.
• DTR operation should be set to normal and DCD operation should be set to normal.
• Avoid gender and serial cable pin adapters (they may introduce potential line interference). Line "noise" can cause your connection to consistently slow down or drop altogether.
• If your computer’s communications card is an older model, it may have a slower and less reliable UART chip such as the 8550. You will get higher speeds (higher than 9600 baud) and greater reliability if you replace it with a newer UART chip such as the 16550 UART.