4. A2CCPU
--------------------
MELSEC·A
(b) A SET instruction is executed only at the leading edge of an input
condition to turn ON an annunciator.
The annunciator stays ON when
the
input
condition is
turned
off.
When a number of annunciators are used, a SET instruction rather
than an OUT instruction is recommended
to
reduce scan time.
I
(2) Turning OFF an annunciator
An RST instruction (RST F[ ]) or LEOR instruction is used to turn OFF
an annunciator.
(a) To turn OFF (reset) the annunciator which has been turned ON, use
an RST instruction (RST F[ ]).
(b) To turn OFF the annunciator which is stored in
09009
and
09125,
use an LEOR instruction.
An example program used to turn OFF an annunciator using an •
LEOR instruction is shown in Fig. 4.23.
Circuit to turn OFF the
first one point
•
LEDR
I--
~ar
ro.ollnput
~a~i,
reset input
I'
DUTYI Kl I Kl I M9020
I--
} Circunto rosotall
L.':j90,L2:.:.0
-c~~~D~O
annunciators
which
areON
I I I > I D9124 I
KO
LEDR
I--
I
",'
~---{~~
~
,---
SET I
FO
I--}
Circuit to turn ON an
L~:-:-:-----:--....!------{J~'I~~
annunciator
, SET I F255
I--
r------1
- ID9124 I
KO
DUTY I
KO
I Kl I 09020
I--
Timing clock is turned
OFF
*
M9020
is used as the timing clock; ON for 1 scan and
OFF
for the next 1 scan
Fig.
4.23
Program
to
Turn
OFF
Annunciator
•
POINTI
When an annunciator (F) is turned ON using an instruction other
than
OUT
and SET instructions, the annunciator has the same function as an internal
relay.
In
this
case, M9009 is not set; annunciator number is
not
stored in 09009,
09124 to 09132, either.
IREMARKI
Setting is possible whetherthe ERROR LED should be lit or blink when an annunciator Is turned
ON. For details, see Section 4.2.8.
4-48
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