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COURIER HIGH SPEED MODEMS APPENDIX E. ADDITIONAL OPERATIONS CONTENTS Voice/Data High Speed/Low Speed Protocol Dedicated and Leased Line Operations Hewlett Packard 3000 Installations MI/MIC Operations Additional Operations E-1 COURIER HIGH SPEED MODEMS VOICE/DATA The voice/data switch is located on the modem's front panel. While the switch's primary function is to toggle back and forth between voice and data communications, this new feature also allows you to perform other functions at the touch of a switch. Set Register S32 for any one of the functions, and change that function any time you wish. NOTE: Use the voice/data switch when the modem is in Command mode (offline). If you press the switch while the modem is online, the modem hangs up and returns a NO CARRIER result code. VOICE/DATA OPERATIONSΩS32=1, S32=2 OR AT COMMANDS When you assemble the Courier, you have the option of plugging your phone into the second modular jack of the modem so it's available for voice calls. You can also switch between the phone and modem during a call. Users of Courier modems have always been able to phone and make arrangements with another user before turning control of the call over to the modems. However, it was difficult to switch from data to voice. Now, if the remote modem has handset exclusion, you can change from voice to data and back again, with or without issuing a command. Handset exclusion means that if the modem is using the phone line, your E-2 Additional Operations COURIER HIGH SPEED MODEMS phone (handset) is automatically dis- connected. However, if you keep the handset off hook, once you hang up the modem the handset takes over the phone line and you can use voice communications again. If the remote user does not have handset exclusion, you may not be able to switch back to voice mode successfully once you have switched to data mode. The following instructions begin with toggling voice/data communications with the switch. These are followed by instructions for doing the same thing with AT commands. Keep in mind that you can use the switch and, if the remote user does not have a switch, he or she can follow the instructions for using the appropriate AT command. Additional Operations E-3 COURIER HIGH SPEED MODEMS Voice/Data SwitchΩS32=1, S32=2 1. Phone the other user to establish the bit rate, parity, word length and number of Stop bits the other person's modem accepts. (Both modems should be offline, in Command mode.) You and the other user must also agree on which modem will go off hook in Originate mode and which in Answer mode. The Courier is factory set to go off hook in Originate mode, S32=1. The Answer modem should have S32 set to 2. NOTE: Either party's device can be the originate or answer modem: it doesn't matter who made the phone call. But one modem must first enter Originate mode and the other then enter Answer mode. 2. Without hanging up the phone, press the voice/data switch. (If S32 is set to 2, Answer mode, press the voice/data switch immediately after the remote user forces the remote modem off hook in Originate mode.) 3. The other party should force the remote modem off hook in Answer mode by pressing the switch. (If yours is the Answer modem (S32=2), the other party should press the voice/data switch immediately before you do so.) 4. If the remote modem has handset exclusion, the remote user should E-4 Additional Operations COURIER HIGH SPEED MODEMS also keep the phone off hook in order to switch back to voice later. If the remote modem doesn't have handset exclusion, you can try to switch back to voice later. Or, you both can hang up your phones as soon as the modems go off hook. Software CommandsΩATD, ATA If your voice/data switch is set for a function other than voice/data operations and you don't wish to change it, use commands. 1. Call the other user to establish the bit rate, parity, word length and number of Stop bits the other person's modem accepts. Determine which modem will originate and which will answer. 2. If you are to originate the connection, type the following command: ATD <Enter> NOTE: Be sure the modem is not set to X2, X4, X6 or X7, or it will return the NO DIAL TONE result code and hang up. 3. The other party must then have the remote modem go off hook in Answer mode. The following command is used to do this: ATA <Enter> 4. If the remote modem also has handset exclusion, leave both phones off hook Additional Operations E-5 COURIER HIGH SPEED MODEMS in case you wish to switch back again to voice after your data transfer. If the remote modem doesn't have handset exclusion, switching back to voice may not be successful. If you don't want to switch back to voice later, hang up both phones as soon as the modems go off hook. ALLOWABLE VOICE/DATA SWITCH FUNCTIONS Use Register S32 to set the voice/data switch for the function you desire. S32 is not bit-mapped. The value for each option is absolute and exclusive. The default is S32=1Ωthe switch forces the modem off hook in Originate mode. You may set the switch to any one of the following functions: S32 Related Value Voice/Data Switch Function Command 0 Disabled Ω 1 Voice/Data+Originate Mode (Default) ATD (Chapt er 7, Appendix C) 2 Voice/Data+Answer Mode ATA (Appen dix C) 3 Redial Last Number ATDL (Chapter 6) 4 Dial Number Stored at position 0ATDS0 (Chapt er 6) 5 Auto Answer On/Off Toggle A TS0=0 or 1 E-6 Additional Operations COURIER HIGH SPEED MODEMS (Chapt er 6) 6 Reset Modem ATZ (Chapter 5) 7 Initiate Remote Digital Loopback AT&T6, S16=8 (Appen dix F) Additional Operations E-7 COURIER HIGH SPEED MODEMS HIGH SPEED/LOW SPEED PROTOCOL OVERVIEW This appendix explains how an answering Courier modem switches its link rate to match the rate of a calling modem. It may be of help also to those users who want to try programming their computers to switch bit rates to match the Courier's connection rate. The material here applies only when the modem is set for variable rates at both the DTE (computer) and link interfaces, &B0 and &N0, respectively. In both Originate and Answer modes, if the link rate is set to &N0, the Courier negotiates with the remote modem to connect at the highest possible rate. In addition, if the modem is set to Extended or Advanced result codes (X1 or higher) it signals the DTE with one of the following result codes or the optional result codes selected with the &An command. CONNECT (300 bps) CONNECT 1200 (1200 bps) CONNECT 2400 (2400 bps) CONNECT 4800 (4800 bps) CONNECT 9600 (9600 bps) The modem sends the result code at its previous rate. Then it switches to the new connection rate. If your computer doesn't switch rates and you want to program it to do so, use the example on the next page as a guide. It demonstrates the occurrence of the CONNECT codes in the connection E-8 Additional Operations COURIER HIGH SPEED MODEMS sequence, so that recognition of the codes can be used to switch the computer. The example uses a sequence of incoming calls, but the codes apply to Originate mode connections as well. The example assumes the following settings: Software: Initially 9600 or 19.2K, or 38.4K bps, allowing the following range of link rates: 9600/4800/2400/1200/300/110 bps Modem: X1 or higher (rate- specific CONNECT codes) &B0 (variable DTE rate) &N0 (variable link rate) NOTE: The HST-mode link rate of 14.4K bps is not included because this link rate requires a fixed DTE rate of 19.2K or 38.4K bps, that is, a modem setting of &B1. Example Modem DTE/DCE Action Response Rate 1. Power on. 9600 2. 300-bps call comes in. RING 9600 CONNECT 9600 3. Data link is established. 300 Data transfer takes place. 4. Data session is over. NO CARRIER 300 Call is ended; loss of Additional Operations E-9 COURIER HIGH SPEED MODEMS carrier. 5. 2400-bps call comes in. RING 300 CONNECT 2400 300 6. Data link is established. 2400 Data transfer takes place. 7. Data session is over. NO CARRIER 2400 Call is ended; loss of carrier. 8. 9600-bps call comes in. RING 2400 CONNECT 9600 2400 9. Data link is established. 9600 Data transfer takes place. 10. Data session is over. NO CARRIER 9600 Call is ended; loss of carrier. E-10 Additional Operations COURIER HIGH SPEED MODEMS Explanation 1. The modem is powered on and is operating at 9600 bps. If the software is then set to 19.2K bps and an AT command sent, the DTE/DCE rate would be 19.2K bps. 2. A 300-bps modem calls. The Courier senses the incoming signal and sends the messages RING and CONNECT to the computer. These messages are sent at 9600 (or 19.2K) bps, the current rate. 3. Since the Courier responds CONNECT, rather than CONNECT 1200, 2400, or 9600, the computer switches to 300 bps. The modem automatically shifts to 300 bps to accept the data from the incoming call. 4. The 300-bps data session is terminated; the modem sends the computer the message NO CARRIER at 300 bps. 5. A 2400-bps call comes in. The modem responds RING and CONNECT 2400. These message are sent at the current bit rate of 300 bps. 6. The computer, receiving the CONNECT 2400 message, adjusts accordingly to the higher bit rate. The modem also shifts to 2400 bps. 7. The 2400-bps data session is terminated; the modem sends the computer the message NO CARRIER at 2400 bps. Additional Operations E-11 COURIER HIGH SPEED MODEMS 8. A 9600-bps call comes in. The modem responds RING and CONNECT 9600. These messages are sent to the computer at the current bit rate of 2400 bps. 9. The computer, receiving the CONNECT 9600 message, adjusts accordingly to the higher bit rate. The modem also shifts to 9600 bps. 10. The 9600-bps data session is terminated; the modem sends the message NO CARRIER at 9600 bps. Keep in mind that whether or not your computer adjusts to these rate changes, the Courier automatically shifts connection rates if it is set to &N0. E-12 Additional Operations COURIER HIGH SPEED MODEMS DEDICATED AND LEASED LINE OPERATIONS The following operations apply in installations where the modem's phone line is not part of a public-access switched telephone network. Instead, the modem is connected to a special user-installed telephone line or a line that is leased from the telephone company. These lines are often referred to as dedicated (to a pair of modems) or private lines. In both types of installation there is a continuous point-to-point connection between two modems. No dialing of phone numbers is required. The modems may be in either Smart or Dumb mode (determined by the position of DIP switch 8). The User-Installed or Leased Telephone Line User-installed lines are most commonly 2-wire lines, similar to the 2-wire lines that connect residential phones to the public switched network. If you are leasing a line from the telephone company, request a 2-wire line, the type of line the modem is designed to work with. If the telephone company only makes a 4-wire line available, you'll need a 4-wire to 2- wire converter at each end of the connection. If the phone company does not install the converters, you will have to supply them. For optimal operations, we recommend that the physical length of these lines not exceed 5 miles. Additional Operations E-13 COURIER HIGH SPEED MODEMS Setting the Modem If the Courier is set to &L1, as described in what follows, and the remote AT-compatible modem has a comparable setting, they automatically connect when they are powered on. They also reconnect, without any operator intervention, if a disturbance on the line is severe enough to break the connection. Set the modem as follows: 1. Set your terminal or communications software to the rate at which you want the modems to communicate. For example, use a terminal/software setting of 19.2K bps and, if both modems have the capability, they will connect at 14.4K bps. The following instructions assume that you are familiar with E-14 Additional Operations COURIER HIGH SPEED MODEMS the guidelines on using the &B and &H commands (Chapter 3 or, in more detail, Chapter 4) and the &W command (Chapter 5). 2. Send the modem the following command: AT &B1 &S2 &H1 &L1 &W <Enter> &B1 fixes the modem's computer interface rate at 19.2K bps. &S2 causes the modem to send a Clear to Send (CTS) signal only after it sends the Carrier Detect (CD) signal, that is, only after it connects with the remote modem. (See the note that follows.) &H1 enables hardware (CTS) flow control. &L1 forces the modems off hook at power on and enables them to re- establish the connection should it be broken. &W writes the settings to nonvolatile memory (NVRAM) as power- on defaults. NOTE: We recommend using the &S2 setting, to delay CTS until after the connection is made, as a precaution. If the modems are in the process of connecting or reconnecting, the Courier interprets any keyboard data entry, including an accidental key stroke, as a key-press abort, and hangs up. Delaying CTS until after carrier detection prevents this from happening, for example, if you are typing data to the remote modem when the modems momentarily disconnect and begin to reconnect. However, you have to set the modem for hardware flow control, &H1. Additional Operations E-15 COURIER HIGH SPEED MODEMS If your software or machine does not support Clear to Send (CTS), don't inlcude &S2 and &H1 in the command string suggested above. Follow the Transmit Data flow control (&H) guidelines in Chapter 4. But keep in mind that if the modems fail to connect or reconnect, the reason could be a key-press abort. 3. Set the modem to load NVRAM settings at power-on, DIP switch 10 UP. It does not matter if the modem is in Dumb or Smart mode (DIP switch 8). 4. Decide which modem is to be the calling modem and which the answering modem. Set the answering modem to Auto Answer, DIP switch 5 UP, and the calling modem to Auto Answer suppressed, DIP switch 5 DOWN. 5. Power off and power on the modems. This initiates the new DIP switch settings and loads the power-on defaults, including &L1. The modems go off hook and establish the connection. NOTE: If the modems cannot restore the connection and you could not set the modem to &S2, the reason could be a key- press abort. If the problem persists, however, you may need to call your telephone company to have them check your line. E-16 Additional Operations COURIER HIGH SPEED MODEMS HEWLETT PACKARD INSTALLATIONS During error control connections, the Courier recognizes the ASCII ENQ/ACK characters exchanged between many Hewlett Packard host computers and their terminals. The HP host sends the terminal an ENQ character at predefined intervals, and sends no more data until the terminal responds with an ACK character. Courier modems manage this ENQ/ACK protocol so that communication is speeded up, thereby enabling HP terminals to achieve high speeds on dial-up lines. Special flow control settings, using the &I command, are required for HP users. These settings apply to ARQ and non-ARQ connections and to Courier modems set to either B0 or B1. Disregard other Courier flow control commands. Set the Courier to Host mode if it is attached to the host computer, or to Terminal mode if it is attached to a terminal, as follows: Host mode AT&I3 <Enter> Terminal mode AT&I4 <Enter> Additional Operations E-17 COURIER HIGH SPEED MODEMS MI/MIC OPERATIONS DESCRIPTION Mode Indicate/Mode Indicate Common (MI/MIC) closure is required by some installations whose existing hardware does the dialing. The modems do not Auto Dial. In these situations, the modem must be forced off hook in Originate mode. This is done by shorting (closing) two of the pins (not Tip and Ring) in the phone connector. The modem is then ready to go online and accept data when it connects with the number dialed by the system equipment. Courier modems are shipped with MI/MIC disabled, that is, for normal use. To set the modems for MI/MIC closure, enable bit 5 of Register S34: ATS34=32 or ATS34 .5=1. We recommend that you write that setting to NVRAM as a power- on default. Once you've set Register S34, have the system force the modem off hook by closing the MI/MIC leads in the phone line connector. The modem's OH (Off Hook) status light, or LED, goes on when the modem goes off hook. TROUBLESHOOTING You may find that the modem does not respond to MI/MIC closure, which you can monitor by observing the LED. Or the modem may fail to go back on hook when the DTE drops the Data Terminal Ready (DTR) signal. The probable reason for E-18 Additional Operations COURIER HIGH SPEED MODEMS either of these conditions is that your phone equipment reverses MI/MIC polarity. It's possible to solve this problem by reversing the modem's MI/MIC wiring. You'll have to dismantle the modem case and reset two switches on the printed circuit board, as follows. 1. Power off the modem and disconnect all of its cables. 2. Turn the modem upside down. Remove the two square vinyl feet near the back of the case, on either side of the bottom label's DIP switch diagram. Be careful to put the vinyl feet aside, upside down, where they won't become stuck to another object. 3. Remove the two Phillips screws. Raise the back end of the case bottom until it is at about a 60° angle; lift it away from inside the front of the modem. Put the case bottom aside. 4. Locate the Voice/Data switch and Volume Control at the front of the modem. Lift up and remove the modem (printed circuit board), carefully easing the Voice/Data switch out of its opening in the front panel. 5. Turn the modem rightside up and locate jumper switches J6 and J8, near the power-adaptor socket. Use Figure E-1 as a guide. Additional Operations E-19 COURIER HIGH SPEED MODEMS Figure E-1ΩCourier Modem Board 6. The jumpers are black shunts that cover two out of three upright metal contacts. As shown in the figure, the modem is shipped with the jumpers over the two contacts on each switch that are closest to the front panel. The third contact on each switch is exposed. Lift off the jumpers from J6 and J8. Reverse the positions shown in Figure E-5.1. That is, on each switch, cover the contact closest to the back of the modem and the contact at the center. Make sure the jumpers cover two contacts on each switch, or you'll disable the MI/MIC function. 7. Replace the modem in the case top: ease the Voice/Data switch into the opening in the front panel; set the Volume Control on its semicircular rack; make sure the back of the board rests on the locator pins at the rear (from which you removed the screws). E-20 Additional Operations COURIER HIGH SPEED MODEMS 8. Reconnect the modem's RS-232, power and phone cables, in that order. Be sure the phone cable is plugged into the jack closest to the center of the modemΩthe jack represented by the wall jack icon on the case bottom label. CAUTION: When you power on the modem there will be potential hazardous voltage, particularly near the phone jacks. Do not touch the board when the power is on. 9. Power on the modem. Try MI/MIC closure again. Check to see that the Off Hook (OH) status light goes on. If you dialed a number, listen for an answer tone from the remote modem. Then drop the DTR signal. The modem should go on hook and the OH status light should go off. 10. If closure is not working properly, review the steps in this appendix. Be sure the jumper switches are in the reverse position of those in Figure E-5.1. If you still have problems, there may be a problem with the phone cable. Or there may be a problem with your hardware. 11. When the equipment is working correctly, replace the bottom of the modem case. Ease the two nibs near the front corners into their openings in the front of the case top, and snap the back of the case bottom into place. Replace the two screws and the two vinyl feet. Additional Operations E-21