Nucleus Support
| Modems 101 |
| This page is designed to help you solve some basic Modem problems. If you are looking for even more information check out ModemHelp.org. |
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Flow Control
Hardware flow control is required for all binary and Zmodem protocol transmission. Hardware flow control uses two leads between a computer and modem to control data flow. The CTS is raised from the modem. The RTS is raised from the PC. This is called RTS/CTS handshaking. If you are using an internal modem you need to set your software to hardware flow control and RTS/CTS handshake. If you are using Microsoft Windows, you need to also change these settings in Windows Control Panel. Consult your modem manual for the right character to enable hardware flow control. Check your modem initialization string to see if it contains this character. If not, then add it to the end of the string. This character switch will tell your modem to initialize hardware flow control. Failure to do this can cause errors in your upload and downloads and a very slow cps throughput. |
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Communications Software
We recommend that you equip your computer with a reliable communications software package. There are several good ones on the market. Crosstalk for Windows, Procomm, and Telix (shareware) are some of the better one's for PC's. For Mac's there is Qualcomm II manufactured by Hayes. Advice to Windows users: Don't use Windows Terminal. It just doesn't work. Although Terminal has vt100 terminal emulation, you will find that your arrow keys won't work. Run Away Screens are another problem that you will encounter. |
| Cancelling Call Waiting during your modem session
Call Waiting can cause your modem to drop carrier. You can temporarily cancel call waiting for the length of your Nucleus client. To do this add a *70 to your dialing string. If your phone has call waiting, be sure and disable it before dialing into Nucleus. |
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Bits and Baud
Sometimes you will see the term baud used in quoting transmission line speed. BPS (bits per second) refers to transmission line speed or the bit rate of a data transmission channel. While signaling speed, or baud, refers to the number of times in each second the line condition changes. In other words, the speed in baud means the number of signal events per second. If a signal event represents only one bit condition, the line speed in baud is the same as the bit rate in bits per second. When each signal event represents other than one bit, baud does not equal bits per second. The terms bps and baud should not be used interchangeably. A general rule is to set your baud rate to 4 times your transmission rate. For example: If you have 14.4 bps modem, your transfer rate is 14.4. 14.4 X 4 = 57600. This means that your 14.4 bps modem will have up to 57600 signal events per second. Nucleus supports v.42 to v.90 bis modem standard. Please locate the character that's unique to your modem. You'll locate this character in your modem manual. Place this character in your modem's initialization string. The v.90 bis modem standard may make a difference in the connection between your modem and our system. v.90 bis is of particular importance when running your PPP Software. |
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