ZCOM Tables and Data Structures
Logical Terminal Tables
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 | Logical Status Format LTSTAT |
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| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 |
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| EN | AC | UP |
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EN - logical terminal enabled (ZCOM_LTSTAT_ENB)
AC - logical terminal activated (ZCOM_LTSTAT_ACT)
UP - logical terminal up (ZCOM_LTSTAT_UP)
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.
LTINST, LTBRCH, LTWORK, 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.
LTNAME - Terminal name
This is a
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).
Chapter 3 | 67 |