PAD Parameters

PAD parameters are defined in the X.3 ITU-T Recommendation and are used to identify and control terminals. These parameters are used to set line feed, data forwarding, echoing, editing, and so forth. The PAD values can be set by the remote access administrator, by the user on a LAN workstation, or by an operator at the host computer.

The remote access software allows you to modify PAD parameters before establishing a connection with a remote host computer. Once you are online with the host computer, you can alter PAD parameter settings using procedures compatible with Recommendation X.28.

Because PAD parameters can differ from one host to another, changes must be made cautiously. Each AIOPAD virtual port maintains its own set of parameters. The PAD parameters that are changed online are valid for the duration of the session only. Once disconnected, PAD parameters revert to their defaults. Table 3 summarizes the PAD parameters and their default values.

Table 3. PAD Parameters with the Default Values

NOTE:  PAD parameters 23 through 25 in Table 1, Commands for Modem-Independent Ports are AIOPAD-specific and are not standard X.3 parameters.

Use the following syntax to read the X.3 PAD parameters:

For example, the characters 1:1 mean the PAD parameter 1 is set to 1.

The following paragraphs describe each PAD parameter more fully.

1. Recall Character

Use this parameter to escape from data transfer state to command mode when the character data link escape (DLE) is transmitted from the terminal.

PAD Values

0: Escape not possible

1: DLE (default)

32 to 126: User-defined escape character

NOTE:  You can also escape from the data transfer state by setting parameter 7 (Break Signal Action) to 8.

2. Echo

Use this parameter to enable all characters to echo on your screen and to be forwarded to the remote DTE.

PAD Values

0: No echo

1: Echo (default)

3. Data-Forwarding Signal

Use this parameter to terminate the assembly of a packet and forward it to the network.

PAD Values

0: No data-forwarding characters

1: Alphanumeric characters (A-Z, a-z, 0-9)

2: CR (default)

4: ESC, BEL, ENQ, ACK

8: DEL, CAN, DC2

16: ETX, EOT

32: HT, LF, VT, FF

64: All other control characters

You can code parameter 3 as a single function or as the sum of any combination of the preceding functions. A useful combination is the value 126, which represents the sum of functions 2 through 64---that is, all control characters and DEL.

4. Idle Timer Delay

Use this parameter to set the time for data forwarding.

PAD Values

0: No data forwarding on timeout (default)

1 to 255: Units of 1/20 second, maximum 255

5. PAD-to-Terminal Flow Control

Use this parameter to instruct the PAD to read data from an auxiliary I/O device. The PAD must exert flow control.

PAD Values

0: No use of X-ON (DC1) and X-OFF (DC3)

1: Use of X-ON and X-OFF for auxiliary devices (data transfer) (default)

6. Service Signal Control

Use this parameter to determine whether or not service signals and the command prompt are transmitted to the terminal.

PAD Values

0: Suppress service signals

1: Transmit service signals other than the prompt

4: Transmit prompt signals only

5: Transmit service signals and prompt signals (default)

7. Break Signal Action

Use this parameter to specify the procedure upon receipt of a break signal.

PAD Values

0: No action (default)

1: Send an interrupt packet

2: Send a reset packet

4: Send to DTE an indication of break packet

5: Send interrupt and indication of break packet

8: Escape from data transfer state

16: Discard output

21: Discard output, interrupt, and indication of break (1+4+16)

The coding of parameter 7 can be a single function or the sum of any combination of functions.

8. Discard Output

Use this parameter to control the discarding of data pending output to the terminal.

PAD Values

0: Do not discard (default)

1: Discard output to terminal

9. Padding after CR

Use this parameter to determine the number of padding characters that the PAD automatically inserts into the character stream transmitted to the terminal following a carriage return (CR).

PAD Values

0: No padding after CR (default)

1 to 7: Number of padding characters after CR

10. Line Folding

Use this parameter to determine the maximum number of printable characters that can be displayed on the terminal before the PAD can send a format effector (CR or LF).

PAD Values

0: No line folding (default)

1 to 255: Number of characters per line

11. Terminal Speed

This parameter is set by the PAD when the terminal establishes a physical connection to the network. It indicates the speed of the terminal in bits per second. This is a read-only parameter.

PAD Values

0: 110

1: 134.5

2: 300

3: 1200

4: 600

5: 75

6: 150

7: 1800

8: 200

9: 100

10: 50

11: 75/1200

12: 2400

13: 4800

14: 9600

15: 19200

16: 48000

17: 56000

18: 64000

32: nonstandard (default)

12. Terminal-to-PAD Flow Control

Use this parameter to enable flow control of received data using X-ON and X-OFF characters. The X-ON character is DC1 Ctrl+Q, and the X-OFF character is DC3 Ctrl+S.

PAD Values

0: No flow control

1: Flow control using X-ON and X-OFF (default)

13. Line Feed after CR

Use this parameter to instruct the LAN workstation to insert a LF character into the data stream after each appearance of a CR character.

PAD Values

0: No LF insertion

1: Insert an LF after each CR in the received data stream

2: Insert an LF after each CR in the transmitted data stream

4: Insert an LF after each CR in the echo to the window (default)

5: Combination of 1+4

6: Combination of 2+4

7: Combination of 1+2+4

You can code parameter 13 as a single function or as the sum of any combination of the preceding functions. Any value from 0 to 7 is valid.

14. Padding after LF

Use this parameter to determine the number of padding characters that the PAD automatically inserts into the character stream transmitted to the terminal following a line feed (LF).

PAD Values

0: No padding after LF (default)

1 to 7: Number of padding characters after LF

15. Editing

Use this parameter to enable the user to edit either at the PC or at the host. If you enable local editing, the user can correct any data buffered locally rather than sending it across the network to the host for later correction. When editing is allowed, the PC monitors characters that are assigned as the delete, cancel, and display characters, or it refers to the editing functions described by parameters 16, 17, and 18.

PAD Values

0: No editing in the data transfer state

1: Editing in the data transfer state (default)

When you set this parameter to allow local editing, data forwarding timers are automatically disabled.

16. Character Delete

Use this parameter (provided local editing was enabled) to specify the character used to indicate that the previously typed character must be deleted from the buffer.

PAD Values

0: No delete character

1 to 126: Delete character

8: DEL character (default)

The standard character defined for this function is the backspace character (08h).

17. Line Delete

Use this parameter (provided local editing was enabled) to specify the character used to indicate that the previously typed line should be deleted from the buffer.

PAD Values

0: No line delete

1 to 127: Line-delete character

24: CAN character, Ctrl+X (default)

18. Line Display

Use this parameter (provided local editing was enabled) to specify the character used to indicate that the previously typed line should be displayed again.

PAD Values

0: No line display

1 to 127: Line-display character

18: DC2 character, Ctrl+R (default)

19. Editing Service Signals

Use this parameter to specify the service signal sent to the terminal once the editing functions described by parameters 16, 17, and 18 are performed.

PAD Values

0: No editing (default)

1: Editing for printing terminals

2: Editing for display terminals (default)

8: Editing using characters from IA5

20. Echo Mask

Use this parameter to specify the characters from the PC echoed by the network. The mask applies only when parameter 2 (echo) is set to 1.

PAD Values

0: No echo mask---that is, all characters are echoed except for X-ON and X-OFF in certain cases (see parameters 5, 12, and 22)

1: No echo of CR

2: No echo of LF

4: No echo of VT, HT, FF

8: No echo of BEL, BS

16: No echo of ESC, ENQ

32: No echo of ACK, NAK, STX, SOH, EOT, ETB, ETX

64: No echo of editing characters as designated by parameters 16, 17, and 18 (default)

You can code parameter 20 as a single function or as the sum of any combination of the preceding functions. If parameter 5, 12, or 22 is set to a nonzero value, then X-ON and X-OFF are not echoed.

21. Parity Treatment

AIOPAD does not support this parameter; therefore, you cannot change the default PAD value.

22. Page Wait

AIOPAD does not support this parameter; therefore, you cannot change the default PAD value.

23. Transparency During Data Transfer Mode

This parameter allows you to configure an AIOPAD port to bypass X.3 processing when data is received and transmitted during data transfer mode.

The possible values are 0 (Transparent Mode OFF) or 1 (Transparent Mode ON). The default value is 0 (OFF).

NOTE:  This parameter is an AIOPAD-specific parameter, not a standard X.3 parameter.

24. User Defined Forwarding Character

This parameter allows you to specify your own data forwarding character tailored to fit your application. For example, if you are using PPP for your data link, you might set this parameter to 0x7E, which is the frame delimiter for a PPP packet.

The possible values are 0 through 0xFF. The default value is 0 (no user-defined forwarding character).

NOTE:  This parameter is an AIOPAD-specific parameter, not a standard X.3 parameter.

25. Inactivity Timeout

This parameter allows you to configure an AIOPAD port so that if there is no data flow for the specified timeout period, the connection is terminated by AIOPAD.

The possible values are 0 to 255 units. Each unit is 10 seconds. For example, a value of 6 specifies a timeout of 60 seconds. The default value is 0 (no timeout).

NOTE:  This parameter is an AIOPAD-specific parameter, not a standard X.3 parameter.