modem status signals

The following acronyms are used with the status lights on an external analog dial-up modem. For some functions, there is more than one acronym that can be used.

Acronym Meaning AA Auto answer mode CA Compression active CD Carrier detect CTR Clear to receive CTS Clear to send DTR Data terminal ready EC Error control active HS High speed (4,800 bps and up) LB Low battery MR Modem ready (data set ready) OH Off hook PWR Power on RI Ringing RNG Ringing RTS Request to send RXD Receiving data RD Receiving data SD Transmitting (sending) data TD Transmitting (sending) data TXD Transmitting (sending) data TM Test mode TR Terminal ready

Modem Status Lights

External modems have the advantage of status lights, which are very helpful when troubleshooting the line.