COURIER HST

                                                                  CHAPTER 7
                                                   QUERIES AND HELP SCREENS


          USER INQUIRIES (In)

          The Inquiry command has eight options.  The most commonly used
          options display the following information:

               ATI3      Call duration
               ATI4      Current settings
               ATI5      NRAM settings
               ATI6      HST link diagnostics summary

          I0   The modem returns a 3-digit product code.  If you have a
               problem and call USRobotics' Technical Support Department,
               you may be asked for this product code.

          I1   The modem performs a checksum of its read only memory (ROM)
               and returns the result to the screen.  This function is used
               only in factory testing.  The modem should always read the
               same number.

          I2   The modem performs a test of its random access memory (RAM)
               and returns either the OK (0) or ERROR (4) result code,
               followed by OK when the test is completed.  You may want to
               use this command as a checkpoint if the modem appears to be
               malfunctioning.

          I3   The modem returns the duration of the last call if set the
               K0.  It displays the actual time if set to K1.  See the
               description of the Kn command in Chapter 5.

          I4   The modem displays its current configuration.  The following
               illustration is an example.

          

                     Figure 7.1 -- Sample Result of ATI4 Command


          I5   The modem displays the configuration stored in nonvolatile
               random access memory (NRAM).

          

                      Figure 7.2 -- Sample NRAM Settings Screen


          I6   During a connection, the modem monitors and stores
               information about link operations.  When the call is ended,
               you can request a diagnostic summary, as in the following
               example.


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                                                                COURIER HST

                                          


                 Figure 7.3 -- Sample Link Diagnostics Screen (ATI6)


               Terms used in the display are self-explanatory except for
               the following:

               Octets              Compressed characters
               Blers               Errors in protocol (non-data) blocks
               Link Naks           Negative acknowledgments (one or more
                                   blocks)
               Link Timeouts       Protocol operations, not the retry
                                   timeout; used in internal testing
               Data Compression    On/Off: indicates if data compression
                                   was negotiated for the call
               Equalization        Long/Short: status of S15 bit 0; long if
                                   bit 0=0, short if bit 0=1
               Fallback            Enabled/Disabled: indicates whether or
                                   not the modems negotiated online
                                   fallback during the connection sequence
          
          I7   The modem returns a product configuration.  If you have a
               problem and call USRobotics' Technical Support, you may be
               asked to read this screen.

          S-REGISTER QUERY (Sr?)

          This command allows you to view the contents of a particular S-
          Register, as in the following example that requests the contents
          of register S0 ("On what ring will the modem answer?"):

                    ATS0? <Enter>

          Most registers store values that can be user-defined.  However,
          two registers that are not user-programmable can be queried for
          the following diagnostic information.

          S17  The reason for a Link Disconnect when two modems try to make
               an ARQ connection and fail, or when the remote modem
               disconnects from an ARQ session.  S17 is used for debugging
               purposes.  If you're having an ARQ-compatibility problem and
               call USRobotics' Technical Support, you may be asked to
               check S17.

          S20  The reason for a NO CARRIER result code when the modem is in
               either ARQ or Normal Mode.  Reasons include user aborts
               (pressing <any key> during dialing), loss of carrier, and
               the automatic hangup that occurs when the modem is set to
               &M5 and calls a modem not operating under error control.




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          PHONE NUMBER QUERY (&Zn?)

          At this command, the modem returns the phone number stored in
          NRAM at position n, as in the following example that includes a
          sample modem response:

                    AT&Z3? <Enter>
                    5551234

          HELP SCREENS

          The Courier HST provides four Help screens:  summaries of the
          basic AT command set, extended ampersand (&) command set, S-
          register functions, and Dial command options.

          Stop/Restart Display

          The following command stops the display. Hold down the Control
          key and type "S":

                    <Ctrl>-S

          To restart the display, use the same command or press <any key>.

          Cancel Display

          Either of the following commands cancels the display.

                    <Ctrl>-C
                    <Ctrl>-K

          Basic Command Set ($)

          At AT$, the Courier displays this command set summary:

                                          


                      Figure 7.4 -- Basic Commands HELP Screen


          Extended Command Set (&$)

          At AT&$, the Courier displays this summary of the ampersand
          command set:

          

                    Figure 7.5 -- Ampersand Commands HELP Screen






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          S-Register Functions (S$)

          At ATS$, the Courier displays a summary of the S-register
          functions:

                                          


                        Figure 7.6 -- S-Register HELP Screen


          Dialing (D$)

          At ATD$, the Courier displays this Dial command summary:

                                          


                       Figure 7.7 -- Dial Command HELP Screen




































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