Omron NX-SL series User Manual

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.

Omron NX-SL series Specifications

General

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