Updated: 11 December 1998

OpenVMS System Management Utilities Reference Manual

13.1 LATCP Description

• Specify operational characteristics for your node and its services
• Turn the state of the LAT port driver (LTDRIVER) on and off
• Display the status of LAT services and service nodes in the network
• Display the status of links created on your LAT node
• Display the status of your LAT node
• Show and zero LAT counters
• Create, delete, and manage LAT ports
• Recall previously entered LATCP commands so that you can execute them again without having to retype them
• Create subprocesses so that you can execute DCL commands without exiting from LATCP

LATCP allows you to control the LAT software on a node and to obtain information from it. For example, you can use LATCP to create services on the local node, to associate a port on the local node with a service or device on a remote terminal server, and to display information about services offered on the local node or on other nodes in the network.

When you use LATCP commands to change LAT characteristics (such as creating a service and associating a port with a service), the changes take effect immediately. However, when the LAT port driver stops, these characteristics are lost. If you want these characteristics to be present the next time you start the LAT port driver, edit LAT$SYSTARTUP.COM by modifying or adding commands to set these characteristics. Then, invoke LAT$STARTUP.COM to start the LAT port driver. (Refer to the OpenVMS System Manager's Manual for more information.)

Format

RUN SYS$SYSTEM:LATCP

Description

To invoke LATCP, enter RUN SYS$SYSTEM:LATCP at the DCL command prompt. At the LATCP> prompt, you can enter the LATCP commands described in the following section.

To exit from LATCP, enter the EXIT command at the LATCP> prompt or press Ctrl/Z.

You can also execute a single LATCP command by using a DCL string assignment statement, as shown in the following example:

$ LCP :== $LATCP $ LCP SET NODE/STATE=ON

LATCP executes the SET NODE command and returns control to DCL.

The following table summarizes the LATCP commands.

Command	Function
ATTACH	Transfers control from your current process to the specified process.
CREATE LINK	Creates LAT data links.
CREATE PORT	Creates a logical port on the local node.
CREATE SERVICE	Creates a service on a service node.
DEFINE/KEY	Assigns a command string to a function key on your keypad.
DELETE LINK	Deletes a LAT data link from a node.
DELETE PORT	Deletes an application port or dedicated port.
DELETE QUEUE_ENTRY	Deletes an incoming queued request from the local node.
DELETE SERVICE	Deletes a service on a service node.
EXIT	Returns the user to DCL command level.
HELP	Displays help text for LATCP commands.
RECALL	Recalls LATCP commands that you entered previously so that you can execute them again.
REFRESH	Refreshes your display screen, for example, after your display has been overwritten by output from some other source.
SCROLL	Allows you to retrieve information that has scrolled off the screen.
SET LINK	Modifies characteristics of LAT data links.
SET NODE	Specifies LAT characteristics for a node.
SET PORT	Maps a logical port on a node to either a remote device on a terminal server or a special application service on a remote LAT service node.
SET SERVICE	Changes service characteristics.
SHOW LINK	Displays the characteristics of links on your node.
SHOW NODE	Displays the characteristics of nodes.
SHOW PORT	Displays port characteristics.
SHOW QUEUE_ENTRY	Displays information about requests, or entries, queued on the local node.
SHOW SERVICE	Displays characteristics of LAT services known to your node.
SPAWN	Creates a subprocess.
ZERO COUNTERS	Resets the node counters, service counters, and link counters maintained by your node.

ATTACH

Transfers control from your current process to the specified process. The LATCP command ATTACH is similar to the DCL command ATTACH. For example, from the DCL command level you can enter the DCL command SPAWN to create a LATCP subprocess without ending your DCL session, execute several LATCP commands at the LATCP prompt, then use the ATTACH command to return to DCL.

Format

ATTACH [process-name]

Parameter

process-name

Specifies the name of a parent process or spawned subprocess to which control passes. The process must already exist, be part of your current job, and share the same input stream as your current process.

Process names can contain from 1 to 15 alphanumeric characters. If a connection to the specified process cannot be made, LATCP displays an error message.

If you specify the /PID qualifier, do not use the process name parameter. If you omit the /PID qualifier, you must use the process name parameter.

To display processes, use the DCL command SHOW SYSTEM.

Qualifier

/PID=pid

Specifies the process identifier (PID) of the process that will have terminal control. When you specify a PID, you can omit the leading zeros. If you specify a PID, do not use the process name parameter. If you omit the / PID qualifier, you must use the process-name parameter.

Description

The ATTACH command allows you to connect your input stream to another process. You can use ATTACH to change control from one process to another. For example, you can use ATTACH to change control from LATCP to the DCL command level (see the following example). While you are at the DCL command level, LATCP remains in a hibernation state until you use ATTACH to return to it.

You cannot use this command if you are logged in to a captive account. (A captive account is an account set up to restrict user access to the system. You cannot access the DCL command level from a captive account.) You cannot specify both a process name and the /PID qualifier.

Example

$ SET PROCESS/NAME="TOP_LEVEL"
$ SPAWN RUN SYS$SYSTEM:LATCP
LATCP> SHOW NODE/ALL
   .
   .
   .
LATCP> ATTACH "TOP_LEVEL"
$
      

In this example, the user enters the DCL command SPAWN to create a LATCP subprocess and uses LATCP to display the status of all nodes known to the local node. After using LATCP, the user enters the ATTACH command to return to the DCL command level.

Creates the LAT data links, which are connections to LAN devices, such as Ethernet or FDDI (Fiber Distributed Data Interface) controllers, that you want your node to use. You must have OPER privilege to use this command.

Format

CREATE LINK link-name

Parameter

link-name

Specifies a name for a LAT data link. A link name can have up to 16 ASCII characters. The characters allowed are as follows:

• Alphanumeric characters: A--Z, a--z, 0--9
• A subset of the international character set: ASCII codes 192--253
• Punctuation characters: dollar sign ($), hyphen (-), period (.), and underscore (_)

You can create a maximum of eight links on your local node. Use the SHOW LINK command for a list of the link names that are defined for your node.

Qualifiers

/DECNET (default)

/NODECNET

Directs LAT protocol to use the DECnet data link address (/DECNET) or the hardware address (/NODECNET) when starting the LAN controller. If you do not specify the /DECNET or /NODECNET qualifier, the default is that the LAT protocol will use the DECnet data link address.

Note that if you enter the CREATE LINK command with the /DECNET qualifier and receive an error message indicating a "bad parameter value," it means the SCSSYSTEMID system parameter is set to an illegal value. To change the value of this parameter, use the following formula:

(1024 * a) + n

In the formula, a is the DECnet area and n is the DECnet computer number. If the value is outside the range of 1025 to 65535, the LAT protocol cannot start.

When you use the /NODECNET qualifier, the LAN device driver code determines which address to use. For example:

• If SCSSYSTEMID is set to 0 but DECnet is already running on an Ethernet controller, the LAN device code allows LAT to use the same address as DECnet (AA-00-04-00-xx-xx).
• If SCSSYSTEMID is set to 0 and DECnet is not running, the 08-00-2B-xx-xx-xx address is used (a different address format is used if your LAN controller is supplied by a vendor other than Compaq).
• If the setting for SCSSYSTEMID is the same as the DECnet node number and DECnet is not running, the LAN device code forces LAT to use the AA-00-04-00-xx-xx address.

If DECnet is configured on the system (or if the system is part of a cluster), SCSSYSTEMID may contain a nonzero value. This is a problem only when the system has 2 or more LAN controllers connected to the same logical LAN.

For example, if your system has an FDDI controller and an Ethernet controller, your site may be configured so that the FDDI ring attached to the FDDI controller and the Ethernet segment attached to the Ethernet controller are bridged by a 10/100 LAN bridge (FDDI-to-Ethernet). In this configuration, it is impossible to run LAT over both controllers.

In such a configuration, you must run LAT and DECnet over the same controller if SCSSYSTEMID is not 0. If you fail to do so, DECnet starts first, which in turn causes the LAT startup on the other controller to fail. This failure occurs because LAT startup tries to use the AA-00-04-00-xx-xx address (the DECnet LAN address) but is prevented from doing so by the data link layer. The LAT startup fails because DECnet is already using this address on a different controller. (In a single logical LAN, all data link addresses must be unique. In this setup, both controllers try to use the same address, which is then not unique.)

The following command (which creates the LAT link) also fails because the LAN driver tries to use the address based on SCSSYSTEMID:

LATCP> CREATE LINK LAT$LINK_2 /NODECNET

If SCSSYSTEMID is set to 0, configuring LAT and DECnet on different controllers is possible. However, in a cluster environment, SCSSYSTEMID cannot be set to 0.

/DEVICE=device-name

Specifies the LAN controller device name for a LAT data link (for example, XEB0:). Only one LAT data link can be associated with a LAN controller. If you enter the CREATE LINK command without the /DEVICE qualifier, LATCP attempts to find an available controller by using a list of possible LAT data link device names. Compaq recommends that you specify a default device name by defining the LAT$DEVICE logical name.

/LOG

/NOLOG (default)

Specifies whether LATCP displays a message confirming that the link was created. If you do not specify the /LOG or /NOLOG qualifier, the default is that no message will be displayed.

/STATE=option

Specifies whether the link will be available for use. STATE can have two options:

ON	Specifies that the created link will be available for use with the LAT protocol running.
OFF	Specifies that the created link will not be available for use.

If you do not specify the /STATE=option qualifier, the default is that the created link will be available for use (ON).

Description

The CREATE LINK command creates a link, or connection, for an OpenVMS node and a local area network (LAN) device (for example, an Ethernet or FDDI controller) and assigns a name to that link. An OpenVMS node can have eight LAN links. Each link must operate on a separate LAN controller and have its own LAN hardware.

If you do not explicitly create a link with this command before entering the SET NODE/STATE=ON command, LATCP automatically creates a link for you. LATCP names the link LAT$LINK and assigns it to the first available LAN controller or LAT$DEVICE, if defined. To establish additional links, use the CREATE LINK command.

Whenever you create a link, specify the LAN controller device name.

Use the SET LINK command to modify link characteristics.

Example

LATCP> CREATE LINK NETWORK_A /DEVICE=XEB0: /STATE=ON
      

This command creates an Ethernet link named NETWORK_A. It specifies the Ethernet controller device XEB0 for that link. The link will be available for use.

Creates a logical port on your local node that connects with a remote device on a terminal server. Alternatively, this command creates a logical port on your local node that connects with a specific service. The service can be offered by a terminal server or associated with one or more dedicated ports on a remote LAT service node.

You must have OPER privilege to use this command.

Format

CREATE PORT [port-name]

Parameter

port-name

Specifies the port name in the form LTAn:, where n is a unique number from 1 to 9999. If the port you specify already exists, LATCP returns the following error message:

%LAT-W-CMDERROR, error reported by command executor -SYSTEM-F-DUPLNAM, duplicate name

If you do not specify the port name, you must specify the /LOGICAL qualifier.

Notes When creating a port, note the following points: Compaq recommends that you assign a logical name when creating a port, instead of specifying a specific LTA device. You cannot use the CREATE PORT and SET PORT commands, along with the DCL command SET TERMINAL, to change the characteristics of a DECserver port unless there is an existing LAT connection to that DECserver.

Qualifiers

/APPLICATION

Specifies that a logical port on your node is an application port. It can be used to connect to a remote device (typically a printer) on a terminal server or to a dedicated port on another LAT service node.

If you do not specify a port type, the default port type is APPLICATION.

Note By default, LATCP creates application LAT devices with the HANGUP terminal characteristic. However, if you want to apply the NOHANGUP characteristic to application LAT devices, you can do so by entering specific LATCP and DCL commands. For example: $ LCP :== $LATCP $ LCP CREATE PORT LTA1234 $ LCP SET PORT LTA1234 /APPLICATION /NODE=terminal-server /PORT=server-port $ SET TERMINAL LTA1234 /PERMANENT /NOHANGUP Note that you can insert the SET TERMINAL command in the SYS$MANAGER:LAT$SYSTARTUP.COM file (enter the command for each LAT device that requires the NOHANGUP characteristic).

/DEDICATED

Specifies that a logical port on your local node is dedicated to an application service. When users on a terminal server (or on another node that supports outgoing connections) request a connection to this service name, they are connected to the dedicated port. Refer to the OpenVMS I/O User's Reference Manual for a description of programming an application service.

After creating a dedicated port on a node, use the SET PORT /SERVICE command to map this port to a service.

/LIMITED

Specifies that a logical port on your local node is limited to a service in the same way a port created using the /DEDICATED qualifier is dedicated to an application service. The difference is that ports created using the /LIMITED qualifier are under the control of the system login image (LOGINOUT.EXE) instead of an application program (a user who connects to a limited service and is assigned to a limited port receives the Username: prompt).

Using the /LIMITED qualifier, you can create a limited number of ports and map them to a specific service offered by the host system. If users are logged in to all of the limited ports for the service, no more connections are allowed to that service (terminal server users receive a "service in use" message).

/LOG

/NOLOG (default)

Specifies whether LATCP displays a message confirming that the port was created. If you do not specify the /LOG or /NOLOG qualifier, the default is that no message will be displayed.

/LOGICAL=(NAME=logical-name[,TABLE=table][,MODE=mode])

Specifies a logical name to be associated with the actual name of the created port. You must specify a logical name if you do not specify a port name.

Note If you have sufficient privileges to create a port, but lack the privilege to assign a logical name, the port will still be created.

You can specify one of the following options for the TABLE keyword:

GROUP	Places the logical name in the group logical name table. You must have GRPNAM or SYSPRV privilege to place the logical name in the group logical name table.
JOB	Places the logical name in the jobwide logical name table.
PROCESS	Places the logical name in the process logical name table. This is the default.
SYSTEM	Places the logical name in the system logical name table. You must have SYSNAM or SYSPRV privilege to place a name in the system logical name table.

You can also specify the name of a specific table. For example, you could specify LNM$PROCESS, which would be the equivalent of specifying PROCESS.

Options for the MODE keyword are:

EXECUTIVE	Creates an executive mode logical name. You must have SYSNAM privilege to create an executive mode logical name.
SUPERVISOR	Creates a supervisor mode logical name.
USER	Creates a user mode logical name.

The access mode associated with the logical name is determined by maximizing the access mode of the caller with the access mode specified by the MODE keyword: the mode with the lower privilege is used.

You cannot specify an access mode with a privilege higher than that of the table containing the logical name. However, if your process has SYSNAM privilege, then the specified access mode is associated with the logical name regardless of the access mode of the caller.

If you omit the MODE keyword, the access mode of the caller is associated with the logical name.

Description

The CREATE PORT command creates a logical LAT port for your local node. You can set up the port as an application port that is later mapped to a remote printer (or other device) on a server, or you can set up the port to be mapped to a dedicated port on a remote LAT service node. See Example 1.

Alternatively, you can set up the port as a dedicated port for a special service on a LAT service node. See Example 2.

You can also create the port as a limited port, using the /LIMITED qualifier.

After creating a port, use the SET PORT command to associate (map) the port with a queue or a service. (See the discussion that follows Example 1.) Ordinarily, you create and set ports in the LAT site-specific startup procedure, LAT$SYSTARTUP.COM. Refer to the OpenVMS System Manager's Manual for more details.

Note When using the CREATE PORT command to create an application port (for example, CREATE PORT LTA5001: /APPLICATION), you might receive an error message similar to the following one: %LAT-W-CMDERROR, error reported by command executor -SYSTEM-F-DUPLNAM, duplicate name This error occurs because the LAT application port that you are trying to create has already been created by some other application. That other application could be LATCP itself because LATCP's port, LATCP$MGMT_PORT, is used to communicate with LTDRIVER. You can avoid creating duplicate ports in two ways: Use the SET NODE/DEVICE_SEED command to move the lower boundary of the device unit number range beyond the LTA devices that you are intending to use as application ports. (By default, LTA device units that originate from the $ASSIGN system service to LTA0: have unit numbers that fall within a range from 1 through 9999.) For example, if you know that all LTA devices from LTA7000: onward are not used as application ports, you could enter the following commands: LATCP> SET NODE/DEVICE_SEED=7000 LATCP> CREATE PORT LTA5001:/APPLICATION . . . LATCP> CREATE PORT LTA5010:/APPLICATION For more information, see the description of the /DEVICE_SEED qualifier in the SET NODE reference section. Execute the LATCP command SET NODE/STATE=ON (either interactively or in a program) before any LTA application or dedicated ports are created. Because every LATCP management port (LATCP$MGMT_PORT) created by the previous LATCP invocation is deleted, no conflict exists with LAT application ports or newly created dedicated ports. For more information, see the description of the /STATE qualifier in the SET NODE reference section.

Examples

LATCP> CREATE PORT LTA22: /APPLICATION 
      

This command creates an application port named LTA22: on a service node. You can associate the port with a specific printer on a terminal server (use the SET PORT /NODE /PORT command) or with a set of printers on a terminal server (use the SET PORT /NODE /SERVICE command). Or, you can associate the port with a dedicated port on a remote service node. In this case, use the SET PORT /NODE /SERVICE command, where the /SERVICE qualifier specifies an application service associated with a dedicated port on the remote node. See the examples for the SET PORT command.

LATCP> CREATE PORT LTA21: /DEDICATED
      

This command creates the LTA21: port. It will be used as a dedicated port that offers a specific service rather than a general timesharing service.

LATCP> CREATE PORT /LOG /APPLICATION -
_LATCP> /LOGICAL=(NAME=MAIL_PORT, TABLE=PROCESS, MODE=SUPERVISOR)
 
      

This command creates an application port. It assigns the name of the new port to the specified logical name (MAIL_PORT). The logical is created as a supervisor mode logical name in the LNM$PROCESS_TABLE logical name table. LATCP displays a confirmation message.

$ LCP :== $LATCP
$ LCP CREATE SERVICE/LIMITED ONLY_ONE
$ LCP CREATE PORT/LIMITED LTA1234:
$ LCP SET PORT LTA1234: /SERVICE=ONLY_ONE
      

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