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GA0383P02 Rev. C
Remote Access
Requirements
· A null modem cable for a direct connection or an external modem capable of 9600 baud
or greater for a dial-up connection (a U.S. Robotics Sportster modem is suggested.).
· A copy of GCM-NET for GCM-A version 2.0 or newer.
· A IBM-compatible personal computer running Microsoft Windows 95, Widows 98 or
Windows NT 4.0.
GCM-A Modem Installation
1. The GCM-A stores a modem setup string in its nonvolatile memory. The setup string is
used to configure the modem to GCM-A requirements. The setup string is specific to the
modem used. The default modem string is for a U.S. Robotics Sportster 28.8 modem.
2. Connect a cable from the 9-pin communication port located on the GCM-A Peripheral
Control Board to the external modem. Configure the modem dip switches (if present) for
three wire communication and Xon/Xoff flow control. (Consult your modem manual for
details).
3. Apply power to the external modem.
4. Choose Initialize Modem from the Setup Menu. The display will indicate “INITIALIZING …”
for about three seconds and then change to “REMOVE MODEM.”
Using a Custom Modem String
The GCM-A is pre-programmed for a U.S. Robotics Sportster 28.8 external modem.
However, the GCM-A is not limited to this modem. The initialization string may be customized
to work with almost any external modem.
The GCM-A supports a three wire communication link to the modem. It expects the modem
to use software flow control (XON/XOFF). It operates at 9600 baud with 8 bits per character
and no parity. It detects an incoming call by listening for a “ring” character (a number ‘2’). It
expects the modem to issue at least two “ring” characters before answering the phone.
The default modem string is “ATE0Q0V0S0=3&D0&R1&H2&I2” where:
· AT — attention
· E0 — turn character echo off
· Q0 — display result codes (need to receive “ring” messages)
· V0 — use numerical result codes (‘2’ instead of “RING”)
· SO=3 — answer on the third ring
· &D0 — ignore DTR (disable hardware flow control)
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