Rockwell Automation 57C610 Enhanced Basic Language, AutoMax - Manual (Page 57)

6Ć17
20 FOR B%=2 TO 10 STEP 2
30 X%(A%,B%)=A% + B%
40 NEXT B%
50 NEXT A%
60 END
6.6 Statements Used for
MultiĆTasking Applications
The typical control application has a variety of functions to perform
and monitor. All of these functions require the attention of the CPU,
or Processor module. To better service these different functions,
BASIC provides a number of multiĆtasking capabilities. MultiĆtasking
is a scheme whereby the operations requiring service are grouped
into separate pieces called tasks.
AutoMax Enhanced BASIC provides the following statements to
allow the user to break the control application into tasks and then
synchronize those tasks:
1. EVENT statement
2. SET statement
3. WAIT statement
4. OPEN CHANNEL statement (INPUT/PRINT channel).
6.6.1 EVENT NAME Statement
An event can be thought of simply as a flag or indicator that one
task can set or raise and another task can wait for. There are two
types of events used in a BASIC task:
1. Hardware events
2. Software events
Hardware events are generated by an actual external condition,
such as an interrupt from a Resolver module (M/N 57C411).
Hardware events cannot be used on the AutoMax PC3000. See
Appendix C for information on allocating hardware interrupt lines. A
software event is simply a flag set by an application task.
An EVENT NAME statement defines a specific event and is used in
conjunction with the SET and WAIT statements. The EVENT
statement defines a symbolic name for an event. The SET and WAIT
statements act on that event. The EVENT statement has two
formats, one for a hardware event and one for a software event:
Software Event
EVENT NAME = event_name
Hardware Event
EVENT NAME = event_name, &
INTERRUPT_STATUS = I/O_variable_name, &
TIMEOUT = timeout_count