Rockwell Automation 57C402 25-115V AC/DC Low Power Output Module - Manual (Page 16)

4Ć2
The frequency with which tasks, or application programs, read their
inputs and write their outputs depends on the language being used.
Ladder logic and control block tasks read inputs once at the
beginning of each scan and write outputs once at the end of each
scan. BASIC tasks read an input and write an output for each
reference throughout the scan.
4.3.1 Ladder Logic Task Example
RUN
STARTPL
1050
light RUN
The symbolic names RUN and STARTPL reference the output
modules that were defined in the configuration.The trailing at symbol
@" is not used in ladder logic tasks. The symbolic name light" is
local to the ladder logic task and does not have I/O associated with it.
4.3.2 BASIC Task Example
1000 LOCAL LIGHT@ \!Fault light
1010 COMMON STARTPL@ \!Start Command
2000 COMMON RUN@ \!Line run
3000 !
4000 !
5000 RUN@ = NOT LIGHT@ AND ( STARTPL@ OR RUN@)
5500 !
6000 END
The symbolic names RUN@ and STARTPL@ reference the output
modules that were defined in the configuration. The symbolic name
LIGHT@ is local to the BASIC task and does not have I/O associated
with it.
4.3.3 Control Block Task Example
2400 COMMON STARTPL@ \!Start command
2500 LOCAL MOMENTARY@ \!Momentary output
3000 !
4000 !
5000 CALL TRANSITION( INPUT=MOMENTARY@,
OUTPUT=STARTPL@)
5500 !
6000 END
The symbolic name STARTPL@ references the output module that
was defined in the configuration. The symbolic name
MOMENTARY@ is local to the control block task and does not have
I/O associated with it.