COURIER HIGH SPEED MODEMS CHAPTER 8. 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 NVRAM settings ATI6 Link diagnostics summary I0 The modem returns a 3-digit product code. If you have a problem and call USRobotics' Technical Support Depart- ment, 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 to K0. It displays the actual time if set to K1. See the description of the Kn command in Chapter 5. Queries and Help Screens 8-1 COURIER HIGH SPEED MODEMS I4 The modem displays its current configuration. Figure 8.1 on the following page is an example. 8-2 Queries and Help Screens COURIER HIGH SPEED MODEMS Figure 8.1êSample Result of ATI4 Command I5 The modem displays the configuration stored in nonvolatile random access memory (NVRAM), as in the following example. Figure 8.2êSample NVRAM Settings Screen Queries and Help Screens 8-3 COURIER HIGH SPEED MODEMS 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. Figure 8.3êSample Link Diagnostics Screen (ATI6) For calls under data compression, the number of characters sent may be less than the number of octets sent, due to buffering operations. Line Reversals only applies to HST-mode operations, when the modems switch the high and low speed channels. At this time, online fallback is only reported Enabled in HST mode. Most terms used in the display are self- explanatory except for the following: Octets: Compressed data units. If the number of octets is greater than the number of characters sent, the modems 8-4 Queries and Help Screens COURIER HIGH SPEED MODEMS probably used MNP5 compression on an already compressed file, and the result was expanded data. Line Reversals: The number of times HST-mode modems switched the high and low speed channels. Blers: Errors in data and protocol blocks. If there were many block errors, your receiver may have experienced problems on the line. Blocks Resent: These represent blocks the remote modem resent due to the previous category, Blers. Link Timeouts: Protocol detection problems: communications were severed momentarily, and the modems probably recovered. This does not indicate the retry timeout. Link Naks: Negative acknowledgments (one or more blocks). Data Compression: Indicates the type of data compression negotiated for the call (V42BIS or MNP5) or NONE. A V42BIS response includes the size of the dictionary and the maximum string length used, for example, 2048/32. See Appendix A for more information. Equalization Long/Short: Status of S15 bit 0; long if bit 0=0, short if bit 0=1. Short equalization applies only to HST modems. Fallback: Enabled/Disabled: indicates whether or not the modems negotiated online fallback during the connection sequence. Queries and Help Screens 8-5 COURIER HIGH SPEED MODEMS Protocol: Indicates the error control protocol negotiated (LAPM, MNP, NONE) or SYNC for a synchronous call. Speed: The last rates at which the receiver/transmitter were operating before disconnecting. Disconnect Reason: Possible reasons the modem hung up are as follows: DTR dropped: The DTE dropped the Data Terminal Ready signal, terminating the call. Escape code: The operator sent the modem the +++ escape code. Loss of carrier: The modem detected loss of the remote modem's carrier and waited the duration specified in Register S10 (default is 0.7 seconds). Inactivity timeout: The modem detected no activity on the line for the duration specified in Register S19 (default is 0, timer disabled). MNP incompatibility: The modem is set to &M5 and the remote modem does not have MNP capability, or there was an MNP negotiation procedure error. Retransmit limit: The modems reached the maximum of twelve attempts to transfer a data frame without error. LD received: The remote modem sent an MNP error control Link Disconnect request. DISC: The remote modem sent a V.42 Disconnect frame. 8-6 Queries and Help Screens COURIER HIGH SPEED MODEMS Loop loss disconnect: The modem detected a loss of current on the loop connecting it with the telephone company central office. This usually occurs because the remote modem has hung up: the central office drops current momentarily when there is a disconnect at the other end of a call. Unless Register S38 is set higher than zero, the modem immediately hangs up at loop loss. Unable to Retrain: After several attempts, disturbances on the phone line prevented the modems from retraining, and they could no longer transmit or receive data. Invalid speed: The modem is set to &N1 or higher, for a fixed link rate, and the remote modem is not operating at the same rate. XID Timeout: The modems failed to negotiate the V.42 Detection (XID Exchange) phase. SABME Timeout (Set Asynchronous Balance Mode Extended): The modems failed this part of V.42 link negotiation. Break Timeout: Incompatible processing of a Break signal occurred. Invalid Codeword: The modem received an invalid V.42 bis (compression) frame. A Rootless Tree: The modem received an invalid V.42 bis (compression) frame. Queries and Help Screens 8-7 COURIER HIGH SPEED MODEMS Illegal Command Code: The modem received an invalid V.42 bis (compression) frame. Extra Stepup: The modem received an invalid V.42 bis (compression) frame. I7 The modem returns a product configuration. If you have a problem and call USRobotics' Technical Support staff, you may be asked to read this screen. 8-8 Queries and Help Screens COURIER HIGH SPEED MODEMS 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? PHONE NUMBER QUERY (&Zn?) At this command, the modem returns the phone number stored in NVRAM at position n, as in the following example that includes a sample modem response: AT&Z3? 5551234 LAST-DIALED NUMBER INQUIRY (DL?) At this command the modem displays the number stored in the last-dialed number buffer: ATDL? HELP SCREENS Courier modems provide four Help screens: summaries of the basic AT command set, extended ampersand (&) command set, S-Register functions, and Dial command options. Stop/Restart Display Queries and Help Screens 8-9 COURIER HIGH SPEED MODEMS The following command stops the display. Hold down the Control key and type "S": -S To restart the display, use the same command or press . Cancel Display Either of the following commands cancels the display. -C -K 8-10 Queries and Help Screens COURIER HIGH SPEED MODEMS Basic Command Set ($) At AT$, the Courier displays a screen that shows a partial summary of the command set. A second screen, activated by pressing any key, shows the remaining commands. The first screen is shown in Figure 8.4. Figure 8.4êSample Basic Commands HELP Screen Extended Command Set (&$) At AT&$, the Courier displays a screen that shows a partial summary of the extended ampersand command set. A second screen, activated by pressing any key, shows the remaining command set. The first screen is shown in Figure 8.5. Queries and Help Screens 8-11 COURIER HIGH SPEED MODEMS Figure 8.5êSample Ampersand Commands HELP Screen Dialing (D$) At ATD$, the Courier displays this Dial command summary: 8-12 Queries and Help Screens COURIER HIGH SPEED MODEMS Figure 8.6êSample Dial Command HELP Screen Queries and Help Screens 8-13 COURIER HIGH SPEED MODEMS S-Register Functions (S$) At ATS$, the Courier displays a screen that shows a partial summary of the S- Register functions. A second screen, activated by pressing any key, shows the remaining registers. The first screen is as follows. Figure 8.7êSample S-Register HELP Screen 8-14 Queries and Help Screens