Real-Time Vista Basic; Real Time Operation - ABB PGC2000 Operation And Service Manual

Ratio Table Number Out of Range: This error occurs when you chain to a nonexistent Vista BASIC
program.
Interpreter Called without Program: The Interpreter was called at end-of-analysis for a program to
be executed according to the program-to-stream assignment, but the program was nonexistent. The
corrective action for this case would be to compile the program.
Time Limit Exceeded: The execution time limit for a given program has been exceeded. The
execution time limit is the actual time for execution as measured by the number of Vista BASIC
instructions executed. Corrective action would be to reduce time needed for execution of a program
by:
a) minimizing the number of statements within loops,
b) reducing the number of statements in a program,
c) minimizing the number of statements that require long times to execute (i.e.,
LPRINT statement).
Insufficient Memory: This error occurs when not enough free memory exists for the interpreter to
dynamically allocate memory for arrays in the DIM statement or for buffers in the LPRINT statement.
The corrective action is to retry the execution when more free memory is available.
Illegal DIM Number: An array dimension (extent) of zero is not allowed in the DIM statement.

REAL-TIME VISTA BASIC

Introduction
Vista BASIC is a programming language that allows the operator to customize some analyzer
operations. Vista BASIC programs can be set up to run manually, at the end of the analysis of a
given stream, or at a specified time of day.
Vista BASIC can also run continuously in the background (this is called running in real time).
Running in real time allows the Vista BASIC program to watch the state of the analyzer and make
decisions based on that state. Six commands in the Vista BASIC language support running in real
time.

Real Time Operation

Only Vista BASIC table number eight can run in real time. If more space is needed, then this table
can chain to another Vista BASIC table. Once it is started manually, table number eight runs
continuously; as soon as it finishes, it starts again.
Table eight can still be used as a normal Vista BASIC table if it is not started manually as Real-Time
Vista BASIC.
How often the table runs depends on how long it takes to execute and what other functions the
analyzer is performing at that time. For example, with the analyzer idle and a very short table, Real-
Time Vista BASIC may run up to forty times per second. At the end of the analysis, Real-Time Vista
BASIC may not run at all for several seconds. At any given time it is difficult to determine how often it
will run.
For this reason, the Vista BASIC table should be written very carefully, taking into consideration table
length and the time required for execution.
2000-OSM, F1 10-43