ACC Programmer's Reference Guide

64 Chapter3
ZCOM Tables and Data Structures
Logical Terminal Tables
LTHLDQ - Sub-packet holding queue
This queue is a holding queue for partial messages to an inbound
multiplexed terminal.
LTDHQN - Data holding queues
For use by an application program to store temporary data for each
terminal. Only the queue header is stored in these fields, as the data
itself is stored in the ZCOM subsystem buffers.
LTUSER - User-maintainable area
The fields in the user-maintainable area may be modified by the zltup
call. The area consists of the following fields (up to the end of the
terminal table):
LTADDR - Logical terminal address
Holds the logical terminal addressing information needed to recognize
the correct logical terminal in a group o f multiplexed terminals. This is a
10-byte field, however the multiplexing program may use these bytes
according to the specific requirements of the protocol.
LTSTAT -Logicalstatus
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 Structure LTSTAT
LTCWCT, LTTXCT, LTRXCT, LTE RCT - Message and error counters
Allow message counters for control writes, transmit data, receive dat a,
and error events to be maintained by the multiplexing application
program, for multiplexed logical terminals.
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EN AC
EN -
AC -
logical terminal enabled (ZCOM_LTSTAT_ENB)
logical terminal activated (ZCOM_LTSTAT_ACT)
UP -
UP
logical terminal up (ZCOM_LTSTAT_UP)