ACC Programmer's Reference Guide

60 Chapter3

ZCOM Tables and Data Structures

Logical Terminal Tables

The Logical Terminal Table (LTT) pages contain the logical configuration

information for each terminal ZLU i n the ZCOM system. Each terminal

table consists of the b asic table (which is fixed for all terminals) and a

table extension (which is of configurable size specified by

LOGICAL-SIZE parameter in the TTGEN configuration file).

The basic table contains common information for all terminal ZLUs. It is

logically divided into two sections; an area reserved for use by the ZCOM

subsystem and a user area that may be manipulated by application

programs (via the zltup routine).

The table extension may be used to store any application defined data

structure and can be m anipulated by the application program that

allocates it (via the zltstore routine).

The layout of a Logical Terminal Table (zltt_type) basic table is shown in

Table 3-9 and Table 3-10. Note that the section reserved for use by the

ZCOM system is immediately followed by the user area.

Table 3-9 Logical Terminal Table (Reserved Area)

Field Name Field Description Field Type Size

(Bytes)

LTZLU Owning terminal ZLU number uns.short 2

LTZCS Owning terminal ZLU checksum uns.short 2

LTMUX MUX i/f number for this terminal uns.short 2

LTPORT Port number within Mux interface uns.char 1

LTTERM Terminal number within port uns.char 1

LTPTERM Pointer to physical terminal table pointer 8

LTGZLK ZLU of next terminal in group uns.short 2

LTDEVC Device type of terminal uns.short 2

LTTYPE Logical type of terminal uns.short 2

LTFLAG System status flags uns.short 2

LTZMXP ZCOM address of multiplexing program struct 6

LTZPRCVR ZCOM addr. of indirect primary receiver struct 6

SPARE1 Reserved, not used int 4