Omron NX-SL series User Manual

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3 Safety Standard Function Blocks
NX-series Safety Control Unit Instructions Reference Manual (Z931)
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SF_CTD
SF_CTD
This FB decrements the counter value when the counter input signal is received.
• The SF_CTD instruction creates a down counter. The preset value and counter value must have a
SAFEINT data type.
• When load signal Load changes to TRUE, counter value CV is set to the value of preset value PV
and counter output Q changes to FALSE.
• When counter input signal CD changes to TRUE, CV is decremented.
• When the value of CV reaches 0 or less, the value of Q changes to TRUE.
• After the value of CV reaches 0 or less, CV does not change even if CD changes to TRUE.
• CD is ignored while Load is TRUE. CV is not decremented.
Instruction Name FB/FUN Graphic expression
SF_CTD Down-counter FB
Variables
Input Variables
Variable Name Data type Valid range Default Description
CD Counter input BOOL TRUE or FALSE FALSE Counter input
LOAD Load signal BOOL TRUE or FALSE FALSE TRUE: Set CV to PV.
PV Preset value SAFEINT 0 to 32767 0 Counter preset value
Output Variables
Variable Name Data type Valid range Default Description
Q Counter output SAFEBOOL TRUE or FALSE FALSE TRUE: CV is 0 or lower.
FALSE: CV is 1 or higher.
CV Counter value SAFEINT 0 to 32767 0 Counter present value
Function
SF_CTD
CD
LOAD
PV
Q
CV

Omron NX-SL series Specifications

General

Brand	Omron
Model	NX-SL series
Category	Control Unit
Language	English