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- Signals.Txt
-
- This file is for all the people wondering what the lights mean. So here
- goes:
-
- Baud Rate - Speed of the Computer-Modem connection
- TD - On if there is data waiting to go from the UART to the modem
- RD - On if there is data in the UART for a program
- CD - Carrier Detect; usually used to tell if the modem-modem link
- is good, but can be forced with certain init strings.
- RI - Ring Indicator; will light at the end of a telephone ring.
- DTR - Data Terminal Ready; means that the computer is ready. Usually
- used to hang up the modem.
- DSR - Data Set Ready; means that the modem is ready. Usually on if
- the modem is on, but may change in self test modes.
- RTS - Request To Send; the computer holds this line high; it does not
- know when it will next have a chunk of data ready for the
- modem. You have to work to get this line low.
- CTS - Clear To Send; indicates the modem is ready for data from the
- computer. Used with high speed modems for handshaking.
-
- These are the signals currently monitored. If the modem is powered up, you
- can usually count on DSR being high. If it is working A-OK, you will
- hardly see a flicker (I haven't yet) on the DSR, RTS, or CTS lines. The
- CTS line might flicker if you have an expensive modem with a large on-board
- buffer connected at a slow speed. Otherwise, Monitor just isn't fast enough
- to catch it.
-
- -Thor Johnson
-
-