User Manual

Siemens Building Technologies VISONIK DCS Functions and System Messages VVS18 CM2U8567E / 04.1999
Landis & Staefa Division Function CB 2-33
Task variables are pre-defined variables with fixed names and are designed for specific
Task control actions for inputs (INPUT) and outputs (PRINT, PLOT).
TSKPRP controls the presentation of Task prompt
TSKTAB defines the tabulator field length of
an output line.
TSKTTY defines a Task's input/output terminal
Task variables can be used as normal variables in Statements, Functions or
Expressions.
The only exception is in FOR statements. Task variables CANNOT be declared as
control variables in FOR/NEXT loops.
With this variable a Task can be assigned to a specific terminal for inputs and outputs.
Allocation is made through the terminal's number.
(Example: TSKTTY:=2). TSKTTY has a default value of 1, i.e. terminal TT1 is used as
the Task terminal.
This variable can only be assigned to an existing and functional terminal unit in the
VISONIK system. Should a terminal unit be in a non-functional state, automatic
changeover to the specified terminal's back-up unit is made.
Assume a system has three terminals - T1, T2 and T3. TSKTTY has been set to 2, i.e.
T2 is the relative Task's terminal. T3 has been declared as the backup terminal (see
point type MC, parameter BCTY). This means that when T2 is faulty all actions are
directed to T3. Terminal changeover is reversed as soon as the original Task device
If the backup terminal is also faulty a backup to the backup is temporarily used.
However, if in this sequence there is no functioning terminal then as a last resort all
INPUT, PRINT and PLOT actions are directed to T1.
If all terminals are faulty the Task messages are lost!
If TSKTTY is assigned a "non-existing" terminal an error message is given.
When editing a Task through Function CB, then -
Dialogue terminal unit = Task terminal unit
Note that TSKTTY only tags the relative input/output terminal for the currently running
Task.
The Task terminal may also be conditionally assigned by setting Task Variable TSKTTY
to -1. In this case the unit which becomes the Task terminal is that one from which the
Task was started with RUN or RESTART (RESTART only if the Task is still inactive!).
In the above case (as different to a "normal" Task terminal), any current dialogue on
such an "own" terminal is interrupted after a Task start to allow action of INPUT, PRINT
and PLOT statements to take place without hindrance!
–
Manual Task start --> The relative dialogue terminal is entered in TSKTTY.
–
Task start from "outsider" Task --> TSKTTY from "outsider" Task is transferred to
TSKTTY of started Task.
–
Task start from a reaction --> The first terminal declared in the Reaction entry's device
mask is assigned to variable TSKTTY in the started Task. If no terminal exists in the
device mask, TSKTTY takes on a value of 1.
Such a conditionally selected terminal remains valid as the Task terminal until either
TSKTTY value is set to a fixed terminal, or the Task is started from another terminal!
TSKTTY : Task Terminal
Device
Example
"Own Terminal Unit"
Important
Rules: