Chapter 6. Configuration
20 sec or EON: The ISU 2x64 assumes the dial string is fully entered if more than 20 seconds elapse since the last digit was keyed, or the unit receives the EON command.
Wait for EON: The ISU 2x64 assumes the dial string is fully entered only if the unit receives the EON command.
AT Commands
Configuring the ISU 2x64 for AT commands enables inband dial- ing over a DTE interface using asynchronous AT commands. AT commands can be used to set up the ISU 2x64 as well as establish and end a call. Calls can be disconnected from the front panel (as described previously) or from the
When AT commands are selected, the DTE port becomes dual purpose. First, while a call is not established, the port accepts AT commands. During this time, the CD signal is inactive. Second, when a call is established, the port is used for data. This data mode is indicated by the CD signal active. See the appendix AT Commands for a listing of the supported AT commands and their functions. In addition to the front panel, the ISU 2x64 can be con- figured and controlled with inband AT commands from an asyn- chronous DTE port just as modems are.
To exit data mode and enter command mode, the asynchronous DTE device must transmit a proper escape sequence to the ISU 2x64. A specified time delay must occur between the last data character and the first escape sequence character. This is the guard time delay, and it can be changed by writing a value to the S12 register. The default value for the guard time is one second. For a valid escape sequence to occur, the DTE must transmit the escape code character three times in succession with delay between each character being less than the guard time. The default escape sequence is +++.
Once command mode is entered, AT commands can be transmit- ted to the ISU 2x64 to configure most of the options, dial remote ISUs, or initiate tests to check both the ISU 2x64 and the network connections. All command lines must begin with the AT charac- ter set in either capital or lower case letters. A command line can
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