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Version 1.73 Copyright © 1997 Link Communications Inc. 1/18/97
Serial Port Interfacing
The RLC-Club has a full duplex serial port for interfacing to a computer or serial terminal; it is
the connector right next to the main power plug. This connection can be made with just a
cable, a telephone modem, a packet TNC, or any other method that will send the serial
characters back and forth (some have even used Telnet over the Internet). You can use this
serial interface to monitor and program the controller. See Appendix F for more information
about controlling from the serial port.
Using a Telephone Modem
There are two ways to control the RLC-Club over the phone line. If the RLC-Club has an
autopatch, you can control it using the reverse autopatch and entering commands with the
telephone's DTMF pad. This works well for small changes, but if you want to do a lot of
programming remotely, it is nice to do it with a computer. You can do this by putting an
external modem on the controller and calling it from a modem attached to your computer
(either internal or external). The modem should be connected to the controller's serial port - it
has nothing to do with the autopatch. You can either run separate phone lines to the autopatch
and the modem, or you can split the phone line and use it for both (one at a time, of course).
You can either have your computer call the modem and have it answer or you can have the
controller call your computer. If you want to call the controller and have the modem answer
and you plan to use the reverse autopatch, you will have to have a way of determining which
one answers the phone. The most common way is to set the modem to answer on three rings,
then to change the reverse patch setup to make it answer on either 1 or 5 rings (you can do that
with a couple of macros). Whichever one answers first will make the connection. It is also
possible to use a call routing interface (similar to a fax switch) to detect whether you are calling
with a modem or not or to make you press DTMF digits to get to the modem.
The other option is to make the controller call your computer. This is usually done by sending
a DTMF command to the controller to tell it to call you, which means you can't connect with
the modem if there is a problem with your receiver. The DTMF command usually calls a
macro that sends "ATDT <phone number>" to the modem (using command 162). The
advantage of having the controller call you is that it doesn't conflict with the reverse patch and
since the phone number is hard coded in the macro, you can be sure that no one else will call
the controller with their modem and get control (since the modem can be set not to answer). If
you plan to use this method, you may have to turn off line feed sending with command 060,
since most modems will abort the dialing process if they receive any more serial characters
after "ATDT<phone number><carriage return character>" and the controller usually sends both
a carriage return and line feed at the end of each line.
Before connecting the external modem to the controller, you should connect it to your computer
or serial terminal and enter some setup commands. Even if you already have a modem in your
computer, you need to hook up the modem that will go on the controller to set it up. You can
use a standard modem cable for this, or build one according to the chart below. Note that this
cable is different than the one that you will use between the controller and the modem, even if
the connectors are the same (pins 2 and 3 are swapped).
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