X25AM Programming Manual

X3PAD Interface
X25AM Programming Manual—527201-001
4-3
Information Exchange
When ITI is the Subdevice Protocol
If the remote device is an application using a subdevice configured for the ITI protocol,
supported by an X25AM process using the ITI protocol, then the subdevice must be
configured as a conversation-mode-only device (type 6, subtype 0).
If the conversational mode parameters are not specified for this subdevice or the
associated line, ITI sends a Q-packet to the PAD with CPADPARMS (13, 4), directing
the PAD to insert a line feed (LF) after a carriage return (CF) is received from the
terminal. This is an example showing use of the Q bit to identify X.29 data.
If any parameters are specified using SCF to configure the PAD for the ITI protocol,
then all desired parameters must be specified. For more information about PAD-ITI
packet exchange, see Section 2, ITI Applications.
Information Exchange
X3PAD exchanges information with the terminal in character mode (conversation
mode) format. X3PAD and X25AM exchange information using the PTP (mode 3)
protocol. Therefore, a qualifying (Q) bit value is included as part of the information.
X25AM exchanges packetized information with the network. This is an example
showing use of the Q bit to identify other user data that is not specifically X.29.
Filtering Output Sent from X3PAD to the Terminal
Control characters embedded in X3PAD output that goes to the terminal may not be
compatible with this device. Depending on the device, X3PAD filters its output so that
there is no compatibility problem. Filtering removes or alters various control characters.
Table 4-1, Table 4-2 on page 4-4, Table 4-3 on page 4-4, and Table 4-4 on page 4-4 list
the kinds of filtering performed by X3PAD.
In Table 4-2 on page 4-4, if the end of the output line has not been reached and there
is a blank space or blank spaces at the end, then the replacement character goes in
the first blank space and the next line is started. Otherwise, there is no replacement
and the next line is started.
Table 4-1. Types of X3PAD Output Filtering
Type of Filtering Output Device Type
No filtering Process
Semi-filtering Printer
Filtering Terminal process
Disk file
AM-filtering AM6520 process
AM3270 process