6100 ADCCP Programming Manual

Line Configuration Options
ADCCP/X21 Protocol Module
069225 Tandem Computers Incorporated 3–3
During call establishment and release, the protocol task manages the interface
between the call-control task and CP6100. The call control task has control over
the X.21 line and has exclusive access to the X.21 driver.
After a network connection is established, the protocol task takes control of the
X.21 line and has access to the X.21 driver.
Call-Control Task The call-control task is responsible for managing the X.21 call establishment and call
clearing procedures. During connection establishment, the call-control task handles
host requests and controls the X.21 driver. All host requests and driver control passes
to the ADCCP protocol module once a connection is established. The call-control task
remains inactive until the connection is released. When a connection release is
requested, the call-control task regains control of the X.21 driver until the release
procedures are complete.
X.21 Driver The X.21 driver manages all physical I/O with the X.21 LIM. The driver is controlled
by the call-control task during call establishment. After an X.21 connection is set up,
the ADCCP protocol module controls the driver. The control of the driver allows the
protocol module to establish the ADCCP protocol over the X.21 link and totransfer
data. If the connection-clearing phase is initiated, driver control is passed back to the
call control task.
Line-Configuration
Options
ADCCP/X21 line-configuration options fall into two groups:
ADCCP configuration options that specify parameters for ADCCP transmission
control, frame format, character code translation, and error handling. You define
these options at system generation, the same as you do for the 6100 ADCCP
protocol module or with a (1) SET CONFIGURATION request.
Configuration options that specify X.21 attributes. These options define values
that the call-control task uses in connection establishment and clearing phases.
You can define these options by issuing a (80) SET X.21 CONFIGURATION
request.
ADCCP Line-Configuration
Options
Most of the 6100 ADCCP line-control and modem-control options are not applicable to
ADCCP/X21. These options refer to features of the RS-232 interface, which have no
application in the X.21 interface. If you specify any of them in the SYSGEN
configuration file, they are ignored by ADCCP/X21.
Note Table 1-2 in Section 1 lists the line configuration options that you can define in SYSGEN to modify
ADCCP protocol attributes.
X.21 Line-Configuration
Options
Table 3-1 lists the ADCCP/X21 line configuration options that modify X.21 interface
attributes. Most of these options are set to default values recommended by the CCITT.
If you need to modify any of the default values, issue a WRITEREAD with a SET X.21
CONFIGURATION request. (See Section 6, “Requests and Responses,” for a
description of the SET X.21 CONFIGURATION request.)