Pc Modem - GE ALPS Instruction Manual

8 LOCAL USER INTERFACE
Other "Hayes-compatible" modems may implement a subset of the full Hayes command set. It is the responsibility of the
customer to determine the exact commands accepted by a particular modem. The proper syntax for entering the Hayes-
compatible commands (sometimes referred to as the "AT" command set) is not described here. Refer to the modem man-
ual for an explanation of this syntax.
The PC modem must be configured for "intelligent" (command recognition enabled) operation. For the Hayes V-Series
2400 SmartModem, this setting is made with an internal jumper. The default settings listed in Section 8.4.2: MODEM CON-
NECTIONS AND SETTINGS are valid for ALPS-Link. The configuration settings critical to the operation of ALPS-Link are
sent to the modem from the software:
+++
(delay 2 seconds)
ATE0L0Q0S7=60V0X4Y0
These are explained in the following table:
Table 8–4: COMMAND SEQUENCE SENT TO MODEM
COMMAND MEANING
+++ Set modem to command mode
AT Modem attention command
E0 disable command state echo
L0 Low speaker volume (desirable, not required)
Q0 Modem returns result codes
V0 Result codes returned in numeric form
X4 Enables result code features
Y0 Disable long-space disconnect
S7=60 Modem hangs up if no connection within 60 seconds
The S7=60 command is present starting with version 1.05 of ALPS-Link. Earlier versions of ALPS-Link do not send this
command, leaving the time out at the default value, which is typically 30 seconds.
If any of the above commands are not recognized by the modem, the modem will not operate properly. In addition to the
configuration settings listed in Table 8–5, it is suggested that the following settings also be made:
&D3: the modem resets on the ON-to-OFF transition of DTR (Data Terminal Ready).
&C1: DCD (Data Carrier Detect) tracks the received carrier signal.
The modem will operate properly without these two settings, but it will not hang up if the appropriate handshaking signal is
lost. An ALPS-Link setting establishes the baud rate, which must match the ALPS baud rate setting. ALPS-Link will then set
the specified PC serial port (COM1, COM2) to the proper baud rate, parity, data bits, and stop bits. If the PC modem is
capable of operating at more than one baud rate, then it must be able to automatically configure its baud rate, character
length, and parity setting by examining the "AT" command prefix.
The ALPS modem must be configured for "dumb" (command recognition disabled) operation. On the Hayes V-Series 2400
SmartModem, this setting is made with an internal jumper. Since the relay sends no configuration commands to its modem,
the required configuration settings must be made before connecting the modem to the relay. Additionally, the modem must
be initialized to the required configuration settings each time modem power is turned OFF and then ON. Depending on the
design of the modem this is accomplished with switch settings via switches or by saving the settings in nonvolatile memory.
GE Power Management ALPS Advanced Line Protection System
8.4 REMOTE COMMUNICATION INTERFACE
8.4.4 ALPS MODEM

8.4.3 PC MODEM

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