Reference Guide
ZCOM Tables and Data Structures
Logical Terminal Tables
Chapter 3 67
LTSTAT - Logical status
Contains the status of the logical terminal. This entry is maintained by a
multiplexing program and will remain unaltered for a normal 1:1
terminal.
Figure 3-3 Logical Status Format LTSTAT
LTCWCT, LTTXCT, LTRXCT, LTERCT - Message and error counters
Allow message counters for control writes, transmit data, receive data,
and error events to be maintained by the multiplexing application
program, for multiplexed logical terminals.
LTAPNO - System application number
This field is initialized by TTGEN based on the value specified in the
Term or Lterm statement in the TTGEN configuration file. This field is
not used by the ZCOM subsystem. It allows applications to recognize the
terminals which are assigned to it. Each ZCOM application which is a
direct receiver of terminal messages should access only those terminals
with its allocated application number.
LTIN ST, LT BRC H, LTWO RK , LTAREA - Terminal logical ID
These logical terminal ID fields describe the owner and location of the
terminal at an application program level. At this level the physical
parameters are not relevant. Because these fields are at an application
level, their contents are largely dependent on the particular application.
LTNA ME - Terminal name
This is a 30-byte ASCII description of the terminal. It is used by the
ZCOM utility programs as well as application programs. The field is
initialized from the desc parameter of the Term or Lterm statements in
the TTGEN configuration file.
The logical terminal table extension follows the basic table, and is used
exclusively by the application programs. The size of this area is specified
in the HLTDSZE field in the ZCOM header table (zheader_type).
15 10987654321011121314
EN AC
EN -
AC -
logical terminal enabled (ZCOM_LTSTAT_ENB)
logical terminal activated (ZCOM_LTSTAT_ACT)
UP -
UP
logical terminal up (ZCOM_LTSTAT_UP)