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3 Safety Standard Function Blocks
3 - 8
NX-series Safety Control Unit Instructions Reference Manual (Z931)
Operation as an Up Counter
When reset signal
RESET
changes to TRUE, counter value
CV
changes to 0 and up-counter output
QU
changes to FALSE.
When up-counter input signal
CU
changes to TRUE,
CV
is incremented. When the value of
CV
reaches the value of
PV
or higher, the value of
QU
changes to TRUE.
After the value of
CV
reaches the value of
PV
or higher, the value of
CV
does not change even if the
value of
CU
changes to TRUE.
Operation as a Down Counter
When load signal
LOAD
changes to TRUE, counter value
CV
changes to the value of preset value
PV
and down-counter output
QD
changes to FALSE.
When down-counter input signal
CD
changes to TRUE,
CV
is decremented. When the value of
CV
reaches 0 or less, the value of
QD
changes to TRUE.
After the value of
CV
reaches 0 or less,
CV
does not change even if
CD
changes to TRUE.
Common Operation for Up and Down Counters
CU
and
CD
are ignored while
LOAD
or
RESET
is TRUE.
CV
is not incremented or decremented.
If both
CU
and
CD
change to TRUE at the same time,
CV
will not change.
If
RESET
and
LOAD
are both TRUE,
RESET
has priority and the value of
CV
changes to 0.
If
RESET
changes to TRUE,
CV
changes to 0, and so
QD
changes to TRUE.
If
LOAD
changes to TRUE, the value of
CV
changes to
PV
, and so
QU
changes to TRUE.
The following table shows the relationship between
RESET
,
LOAD
,
CV
,
QU
, and
QD
. This assumes
that the value of
PV
is larger than 0.
RESET
Load
CV
QU
QD
Operation
FALSE
FALSE
0 or lower
FALSE
TRUE
Only an up counter operation is
performed.
CV
is incremented when
CU
changes to TRUE.
It is not decremented when
CD
changes to TRUE.
Between 0
and
PV
FALSE
FALSE
Both up and down counter opera-
tion is performed.
CV
is incremented when
CU
changes to TRUE and decre-
mented when
CD
changes to
TRUE.
PV
or higher
TRUE
FALSE
Only down counter operation is
performed.
CV
is decremented when
CD
changes to TRUE.
It is not incremented when
CU
changes to TRUE.
TRUE
FALSE
0
FALSE
TRUE
The up counter is reset.
The value of
CV
is set to 0.
FALSE
TRUE
PV
TRUE
FALSE
The down counter is reset.
The value of
CV
is set to
PV
.
TRUE
TRUE
0
FALSE
TRUE
The up counter is reset.
Reset
takes priority over
Load
.
The value of
CV
is set to 0.
Summary of Contents for NX-SL series
Page 8: ...CONTENTS 6 NX series Safety Control Unit Instructions Reference Manual Z931 ...
Page 28: ...Sections in this Manual 26 NX series Safety Control Unit Instructions Reference Manual Z931 ...
Page 98: ...2 Standard Functions 2 64 NX series Safety Control Unit Instructions Reference Manual Z931 ...
Page 104: ...2 Standard Functions 2 70 NX series Safety Control Unit Instructions Reference Manual Z931 ...
Page 110: ...2 Standard Functions 2 76 NX series Safety Control Unit Instructions Reference Manual Z931 ...
Page 265: ...I 1 I NX series Safety Control Unit Instructions Reference Manual Z931 Index ...
Page 268: ...I 4 NX series Safety Control Unit Instructions Reference Manual Z931 Index ...
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