HP X.25/9000 User's Guide HP-UX 11i v3 (5900-1523, August 2011)

Modifying parameters
Initial parameter settings can be changed at any time during a call. This occurs when x29server
detects an ioctl() call to configure the PTY for a PAD terminal. This system call could be issued
by the UNIX login process, by a shell initialization script such as .login, or by an application.
Each ioctl() request is examined by the server. If a mapping exists between the terminal I/O
parameter and X.3, the terminal I/O value is checked against the current X.3 setting. If the request
calls for a change, the current X.3 setting is overwritten on the server. A set command is sent to
reset the parameter in the remote PAD. If x29server cannot map the terminal I/O parameter to
X.3, the request is processed as a normal terminal I/O ioctl().
When x29printd and x29server transform terminal I/O parameters into X.3 parameters, they
intercept the ioctl (tcseta) call and send an X.29 set command with new X.3 parameter
values if necessary. The related X.3 parameters are: 2 (echo), 3 (data forward), 4 (idle timer), 5
(device control), 12 (flow control), 15 (editing), 16 (character delete), and 17 (line delete).
The x29server process downloads only those X.3 parameters that are specified in the x3config
file for a particular remote system. The x29print process always downloads a set of X.3
parameters (if they exist in the x3config file) at the beginning of a connection, or the default X.3
parameters (given in the preceding table) if the X.3 parameters do not exist in the x3config file.
The X.3 parameters for padem can be changed by an X.29 set message from the remote host or
by the terminal operator with a set command.
Default X.3 parameters
If the x3config file does not have a definition for a particular device, the defaults (listed in the
next section) are used. See “X.25 Configuration files and examples” (page 144) for an example of
the x3config file.
X.3 Parameter descriptions
The following pages contain a description of X.3 parameters 1 through 22. The default X.3
parameters vary for each PAD service.
NOTE: Parameters 1 to 18 are available for networks using either the 1980 or 1984 standard.
Parameters 19 through 22 only apply to the 1984 standard.
Table 30 X.3 Parameter descriptions
DescriptionX.3 Parameter
Specifies whether or not the terminal user will be allowed to escape from data transfer
mode in order to send PAD command signals. 0 indicates escape is not allowed, 1 permits
1 - ESC/Data Transfer
escape from data transfer mode with Ctrl-P, 32 to 126 permits escape from data transfer
mode with the defined character.
Specifies whether or not the PAD echoes to the local terminal all the characters received
from that device. 1 turns echoing on; 0 turns echoing off.
2 - Echo
Specifies one of the defined sets of characters for use as a data forwarding signal. When
one of the characters in the set is received from the terminal, the PAD terminates the
3 - Data Fwd Signal 1
assembly of a packet and forwards it to the remote host. The possible values are listed
below.
MeaningValue
No data forwarding character.0
Alphanumerics.1
Carriage Return only. (This is the default.2
X.3 Parameter descriptions 113