Contents:

Connecting to your ISP

Using the AT Command Set

Upgrading your Modem

Modes of Operation

Dialing, Answering, and Hanging Up

Working with Memory

Controlling Result Code Displays

Controlling EIA-232 Signaling

Accessing and Configuring the Courier 56K Corporate Modem Remotely

Controlling Data Rates

Dial Security

Flow Control

Handshaking, Error Control, Data Compression, and Throughput

Displaying Querying and Help Screens

Testing the Connection

Dedicated/Lease Line and Synchronous Applications

Troubleshooting

Appendixes

S-Registers

Alphabetic Command Summary

Flow Control Template

Result Code Meanings and Sets

Technical Information

V.25 bis Reference

ASCII Chart

Fax Information for Programmers

Viewing LEDs

Regulatory Information

Glossary

Courier 56K Corporate Modem Command Reference

Dedicated/Leased Line and Synchronous Applications

Note: Synchronous Applications typically are mainframe computer based. Standard dial-up ISP is NOT synchronous.

This chapter contains information about:

Overview

This chapter will apply when you want the modem to work with devices that communicate using synchronous protocols (i.e., mainframe computers). The Courier 56K Corporate modem must be connected to a synchronous serial port.

There are two ways to operate your modem in analogue synchronous mode:

Dial Using
Means
V.25bis Software Configuring the modem to enter synchronous mode when you power it on. Then, running communications software that uses the V.25 bis protocol to control the dialing process.
AT Commands Configuring the modem to dial out using AT commands and then switching to synchronous mode once a connection is made.


Requirements for Analogue Synchronous Applications

The information below describes device requirements.

Note: Find out what hardware and software you need before proceeding.

A Device with a Synchronous Serial Port

You will probably have to purchase and install a synchronous adapter card. These cards provide:

  • A synchronous serial port.
  • Support for one or more synchronous protocols.
  • Additional software functions. For example, the card may tell the mainframe what type of computer or terminal you are using. The card may also tell the mainframe what resources you want to use.

A Serial Cable

Obtain a shielded serial cable with a male DB-25 connector on one end and a connector on the other end that is appropriate for your synchronous serial port. Your modem provides an EIA-232 interface through its serial port.

Transmit and Receive synchronous timing pins are required at the EIA-232 interface, so pins 15 and 17 are required. The modem transmits timing signals through pin 15 and receives timing signals through pin 17.

Note: The serial cable included with your modem only supports asynchronous mode.

Communications Software

The devices at both ends of the link must use the same synchronous protocol.

Ask your network administrator about the software support (for example, a specific communications package) that you need to log into the network.

Synchronous Operations

During synchronous operations, transmit and receive clocks at both ends of the phone link control the precise timing of the data flow. The communications equipment at the remote device, your modem, and your computer must all handle the data at the same speed.

Your modem is usually the source of the transmit clock timing signals and sends them to your computer over the EIA-232 interface. Your computer’s rate will follow the connection rates.

 

Configuring the Courier 56K Corporate Modem for Leased Line Operation

You can use the Courier 56K Corporate modem in either smart or dumb mode (determined by the position of DIP switch 8).

If you are using your modem on a leased or dedicated line, it is set to &L1, and the remote modem has a comparable setting, the modems 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.

  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 9600 bps and, if both modems have the capability, they will connect at 9600 bps.

  2. Send AT&B1&S2&H1&L1&W to the modem.

    &B1
    		 Fixes the Courier 56K Corporate modem's serial port rate at the same rate you selected when setting up your communications software.
    &S2
    		 Causes the Courier 56K Corporate 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.
    &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 (for leased lines only).
    &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 56K Corporate modem 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. However, you have to set the Courier 56K Corporate modem for hardware flow control by sending AT&H1.

    If your software or machine does not support Clear to Send (CTS), don't include &S2 and &H1 in the command string as suggested above. But keep in mind that if the modems fail to connect or reconnect, the reason could be a keypress abort.

  3. Set DIP switch 10 OFF. This tells the Courier 56K Corporate modem to load NVRAM settings at power-on. It does not matter whether the Courier 56K Corporate 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.

  5. Set the answering modem to Auto Answer, DIP switch 5 OFF, and the calling modem to Auto Answer suppressed, DIP switch 5 ON.

  6. 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 did not set the Courier 56K Corporate modem to &S2, the reason could be a keypress abort. If the problem persists, however, you may need to call your telephone company to have them check your line.

 

Dial Using V.25 bis Software

To make synchronous connections using V.25 bis communications software, you must first configure your modem using AT commands. Once the modem is configured, run your communications software.

Configuring the Courier 56K Corporate Modem

Before you attempt to connect to a synchronous network, you must first configure your modem using an asynchronous device, such as a terminal or a computer running standard asynchronous communications software.

  1. Find out the protocol being used for dialing and answering in your software and then set your modem to dial using it.

    For your modem to
    Command

    Dial using the BISYNC protocol.

    Your modem and the remote device must use the same 8-bit data format. The character length must be 7 bits and either ODD or EVEN parity (ODD is preferred), or 8 bits and NO parity.
    AT&M6
    Dial using the High Level Data Link Control (HDLC) protocol.
    AT&M7

    Example:     Sending AT&M7&W would select HDLC.

  2. Set the offline clock speed, or the clock speed to be used (between your modem and the computer to which it is directly attached) when the modem is not engaged in a synchronous connection.

    For an offline clock speed of Command
    1200 bps AT%N2
    2400 bps AT%N3
    4800 bps AT%N4
    7200 bps AT%N5
    9600 bps AT%N6 (Default)
    12000bps AT%N7
    14400 bps AT%N8
    16800 bps AT%N9
    19200 bps AT%N10

    Example: Sending AT%N10&W selects an offline clock speed of 19200 bps.

  3. Choose a connection rate to be used (between the Courier 56K Corporate modem and the remote communications device) when the Courier 56K Corporate modem is online.

    If &Nn is set for 2-10, the Courier 56K Corporate modem ignores the %Nn rate and uses the &Nn rate as the online connection rate.

    To set the connection rate to Command
    Variable AT&N0 (Default)
    Reserved AT&N1
    1200 bps AT&N2
    2400 bps AT&N3
    4800 bps AT&N4
    7200 bps AT&N5
    9600 bps AT&N6
    12.0 Kbps AT&N7
    14.4 Kbps AT&N8
    16.8 Kbps AT&N9
    19.2 Kbps AT&N10
    21.6 Kbps AT&N11
    24.0 Kbps AT&N12
    26.4 Kbps AT&N13
    28.8 Kbps AT&N14
    31.2 Kbps AT&N15
    33.6 Kbps AT&N16
    28000 bps AT&N17
    29333 bps AT&N18
    30666 bps AT&N19
    32000 bps AT&N20
    33333 bps AT&N21
    34666 bps AT&N22
    36000 bps AT&N23
    37333 bps AT&N24
    38666 bps AT&N25
    40000 bps AT&N26
    41333 bps AT&N27
    42666 bps AT&N28
    44000 bps AT&N29
    45333 bps AT&N30
    46666 bps AT&N31
    48000 bps AT&N32
    49333 bps AT&N33
    50666 bps AT&N34
    52000 bps AT&N35
    53333 bps AT&N36
    54666 bps AT&N37
    56000 bps AT&N38

    Example:
    Sending AT&N10%N10&W selects a connection rate and an offline clock speed of 19200 bps.

    We recommend that you fix the rate between the computer or terminal and Courier 56K Corporate modem (%Nn) and that you set the connection rate (&Nn) to match. This avoids dramatic changes in the rate produced when the connection rate adjusts to the offline clock speed.

  4. Choose whether the modem should display normal or extended synchronous result codes.

    Depending on the setting of the Xn command, the modem displays normal or extended synchronous result codes. Extended result codes provide more detailed information. Don’t be concerned if synchronous result codes do not appear on your screen they are intended for your communications software.

    By default, your modem is set to X1 for extended result codes. To change to normal result codes, send ATX0 to the modem.

    Example: Sending ATX1&W selects extended result codes.

  5. Your modem is able to answer calls automatically.

    For your modem to Command
    Disable Auto Answer. ATS0=0 (Default)
    Enable Auto Answer. ATS0=1

    Note: Due to the nature of synchronous dial-up, if AA isn’t set up in either the hardware or the software, the Courier 56K Corporate modem auto answers only on the fourth ring.

    Alternatively, you can combine all the previous commands into a compound command, like this:

    AT&M7&N10%N10X1S0=1&W

    This tells the modem to use the HDLC protocol for dialing, an offline clock speed and connection rate of 19200 bps, display extended result codes, auto answer incoming calls, and write these settings to NVRAM.

  6. Set DIP switch 10 OFF and then power the modem OFF, and then ON. Setting DIP switch 10 OFF causes the modem to read the settings you just made from NVRAM, enabling synchronous operation.

Dialing Using V.25 bis

Your communications software, which must support V.25 bis, handles the dialing. Once the synchronous connection is made and the modem is in synchronous mode, V.25 bis commands are no longer necessary and are ignored. For dialing instructions, refer to the manual included with your communications software.

Hanging Up

Since your modem cannot accept commands once it is connected in synchronous mode, you cannot use the ATH (hang-up) command or +++ (the escape code).

The only way for the modem to disconnect is to drop its Data Terminal Ready (DTR) signal. Either power off the Courier 56K Corporate modem or use your communications software (check the software user’s manual for instructions).

Returning to Asynchronous Mode

Once you've completed a synchronous session, you can switch back to asynchronous mode by flipping DIP switch 10 ON and then turning the power of the Courier 56K Corporate modem back on. The Courier 56K Corporate modem cannot switch between synchronous and asynchronous modes while a call is connected.

 

Synchronous Dialing Using AT Commands

To use AT commands to dial, you must set the modem to enter online synchronous mode after you dial. Then, you dial the remote device’s number using AT commands. Once the remote device answers, the modem switches to synchronous mode and starts sending synchronous timing signals to your computer.

Because the modem will not accept commands when it is in synchronous mode, you must configure it in asynchronous mode before connecting to a synchronous network.

The Courier 56K Corporate modem always generates the Transmit clock-timing signals when in synchronous mode.

Note: Data Terminal Ready (DTR) override must be OFF when using modem in online synchronous mode. Use &D1 or &D2. See the Controlling EIA-232 Signaling chapter in this guide.

Configuring the Courier 56K Corporate Modem

  1. If your communications software isn't running, load the program and start Terminal mode (see your software user’s guide for instructions).

  2. Send AT&F0B0&X0 to the modem.

    The device you are calling should also be set to the equivalent of B0, which tells the modem to use the V.25 answer sequence, and &X0, which identifies the modem as the source of synchronous timing signals.

  3. Set the connection rate to be used (between your modem and the remote communications device) when the modem is online.

    First try a variable connection rate of &N0. If that doesn't work, try a fixed connection rate of &N6 (9600 bps) or &N3 (2400 bps).

    • If your modem is set to a fixed rate, and the remote device is not set to the same rate, the Courier 56K Corporate modem hangs up.
    • Your modem cannot connect at 21.6 Kbps in synchronous mode.
    • This modem does not support synchronous communications under HST, V.FC, x2, and V.90 modulations.

  4. Your modem is able to automatically answer calls.

    For your modem to
    Command
    Disable automatic answering
    ATS0=0 (Default)
    Enable automatic answering
    ATS0=1

    Note: Due to the nature of synchronous dialup, the Courier 56K Corporate modem auto answers only on the third or fourth ring.

  5. Send AT&M1 to have your modem enter synchronous mode, followed by the number to dial. Dial should be the last command before the Carriage Return.

    Example: AT&M1DT5551234

    Alternatively, you can combine all the previous commands into a compound command, like this:

    AT&F0B0&X0&N0S0=1&M1*V2=4DT5551234

    This tells your modem to load the "no flow control" factory template and then use the ITU answer sequence, making your modem the source of timing signals. This command sets a variable connection rate and causes your modem to auto-answer incoming calls, switch to online synchronous mode after connection, and then dial 555 1234.

Dialing

There are two methods of autodialing a stored telephone number: You can have the modem dial the stored number either when it receives the Data Terminal Ready (DTR) signal from your computer or at power-on/reset.

  1. Store a telephone number to memory position 0 using the AT&Z0=n command.

    For example, AT&Z0=T18475551111, stores the telephone number 847 555 1111, and tone dial.

  2. Follow step a or b, depending on the dialing method you choose.

    For the modem to dial when
    Type
    It receives the DTR signal from your computer
    ATS13.3=1&W
    Modem is reset
    ATS13.4=1&W


  3. Make sure DIP switch 10 is set to OFF to load settings from NVRAM.

Hanging Up

When one of the following events occurs, the modem returns to asynchronous Command mode:

  • Your modem remains online until the remote device disconnects.
  • Your software causes the DTE to drop the Data Terminal Ready signal (DTR).
  • You power off the modem.

 

Auto-Dialing

Because the Courier 56K Corporate modem will not accept commands when it is in synchronous mode, you must configure it in asynchronous mode before trying to connect to a synchronous network.

Then you can set the Courier 56K Corporate modem to dial the remote device at power-on, when it receives the DTR signal from your computer, or when you press the Voice/Data switch.

Once the remote device answers, the Courier 56K Corporate modem switches to synchronous mode and starts sending synchronous timing signals to your computer.

Configuring the Courier 56K Corporate Modem

  1. If your communications software isn't running, load the program and start Terminal mode (see your software user's guide for instructions).

  2. Send AT&F0B0&W to the modem.

    The device that you are calling should also be set to the equivalent of B0, which tells it to use the ITU answer sequence.

  3. Select a source of the synchronous timing signals. For example, send AT&X0&W to select the Courier 56K Corporate modem as the source of the synchronous transmit clock timing signals.

    For your modem to
    Command
    The Courier 56K Corporate modem sends transmit clock timing signals to the DTE over the serial interface. DTE rate follows the connection rate.
    AT&X0 (Default)
    The DTE sends transmit clock timing signals to the Courier 56K Corporate modem over the serial interface. Typical use: multiplexed leased lines.
    AT&X1
    The Courier 56K Corporate modem sends receiver clock timing signals, which are looped to the transmit clock and sent to the DTE over the serial interface. Typical use: systems that require synchronisation of data flowing in both directions.
    AT&X2

  4. Set the connection rate to be used (between the Courier 56K Corporate modem and the remote communications device) when the Courier 56K Corporate modem is online.

    Try a variable connection rate first, AT&N0. If that doesn't work, try a fixed connection rate of &N10 (19.2 Kbps), &N6 (9600 bps), or &N3 (2400 bps).

    Command
    Rate
    AT&N0
    Variable (default)
    AT&N1
    Reserved
    AT&N2
    1200 bps
    AT&N3
    2400 bps
    AT&N4
    4800 bps
    AT&N5
    7200 bps
    AT&N6
    9600 bps
    AT&N7
    12 Kbps
    AT&N8
    14.4 Kbps
    AT&N9
    16.8 Kbps
    AT&N10
    19.2 Kbps
    AT&N11
    21.6 Kbps
    AT&N12
    24 Kbps
    AT&N13
    26.4 Kbps
    AT&N14
    28.8 Kbps
    AT&N15
    31.2 Kbps
    AT&N16
    33.6 Kbps

    • If the Courier 56K Corporate modem is set to a fixed rate, and the remote device is not set to the same rate, the modem hangs up.
    • Courier 56K Corporate modems cannot connect at 21.6 Kbps or higher in synchronous mode.
    • HST and V.FC modulations do not support synchronous communications.

  5. If the Courier 56K Corporate modem is to answer calls, enable automatic answering by setting DIP switch 5 OFF.

  6. Send AT&M1&W to the modem to enter synchronous mode.

  7. Store a telephone number to memory position 0, using AT&Z0=phone number.

    For example, to store 847 555 1111, and tone dial, type AT&Z0=T18475551111

  8. Select a method to use to autodial the stored number. You can have the Courier 56K Corporate modem dial the stored number when it receives the Data Terminal Ready (DTR) signal from your computer, at power on/reset, or when you press the Voice/Data switch.

    Use the following table to determine which command you need to send to your modem for the dialing method you choose.

    For your Courier 56K Corporate modem to dial
    Command
    When it receives the DTR signal from your computer.
    ATS13.3=1&W
    When you power your modem on or reset it.
    ATS13.4=1&W
    When you press the Voice/Data switch.
    ATS32=4&W


  9. Make sure that DIP switch 10 is OFF, to load settings from NVRAM.