10 CPU Unit Functions
10-16
CJ2 CPU Unit Software User’s Manual
z Programming without Background Execution
As shown below, processing is completed when the instruction is executed.
z Programming with Background Execution
With background execution, the program is changed so that MAX(182) is executed only when the
specified Communications Port Enabled Flag is ON (i.e., only when the port is not already being
used for background execution or network communications). Also, input conditions are controlled
with SET and RSET instructions to ensure that processing is performed in the correct order. (Com-
munications port 0 is used for background execution in the following example.)
Programming Example 1
MAX
D0
D100
D200
a
SUM
D2
D100
D201
Execution condition
MAX(182) is executed completely
as soon as the execution condition
"a" turns ON.
SUM(184) can be executed
immediately after MAX(182).
RSET
a
SET
b
MAX
D0
D100
D200
a A202.00
RSET
b
SUM
D2
D100
D201
b A202.00
SET
c
c
A202.00
Communications
Port Enabled Flag
Execution
condition
MAX(182) execution is started if
execution condition "a" is ON and
the Communications Port Enabled
Flag is ON.
Execution condition "b" is turned
ON to enable the next
background instructions (here,
SUM(184)).
"a" is turned OFF so that MAX
(182) will not be executed in the
next cycle.
Communications
Port Enabled Flag
Execution
condition
SUM(184) execution is started if
execution condition "b" is ON and
the Communications Port Enabled
Flag is ON (i.e., when MAX(182)
execution has been completed).
"b" is turned OFF so that SUM(184)
will not be executed in the next
cycle.
Execution of SUM(184) has been
completed when "c" is ON and the
Communications Port Enabled Flag
is ON.
"c" is turned ON to enable
confirming the completion of SUM
(184).
Confirmation of
completion of
background
execution
Execution
condition
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