ZCOM Tables and Data Structures

Logical Terminal Tables

Logical Terminal Tables

The Logical Terminal Table (LTT) pages contain the logical configuration information for each terminal ZLU in the ZCOM system. Each terminal table consists of the basic table (which is fixed for all terminals) and a table extension (which is of configurable size specified by LOGICAL-SIZEparameter 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 manipulated 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

Size

Type

(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

 

 

 

 

62

Chapter 3