2 Instruction Descriptions
2-4
NJ-series Instructions Reference Manual (W502)
The specifications of variables that are used for many instructions (EN, ENO, Execute, Done, Busy,
Error, ErrorID, and ErrorIDEx) are described below. These variables are not described in the tables of
variables for individual instructions. Check the graphic or ST expression for the instruction to see if an
instruction uses these variables.
EN is an input variable that gives the execution condition for a FUN instruction.
When you use a FUN instruction in a ladder diagram, connect the execution condition to EN.
* If upward differentiation (@) is specified as an instruction option, the execution condition is when the value of EN changes
from FALSE to TRUE. If downward differentiation (%) is specified as an instruction option, the execution condition is when
the value of EN changes from TRUE to FALSE.
• FB instructions do not have an EN input variable.
• When you call a FUN instruction from structured text, omit the EN input variable. The EN input vari-
able is not required in structured text because the execution condition for the instruction is deter-
mined by the operation sequence.
The ENO output variable passes the execution to the next instruction in a ladder diagram. Normally,
when instruction execution is completed, the value of ENO changes to TRUE. Execution of the next
instruction is then started.
* ENO is TRUE only while the execution condition is met. The value of ENO changes to FALSE when the execution condition
is no longer met after a normal end.
• Most FUN instructions and FB instructions have ENO output variables. There are, however, some
instructions that do not have an ENO output variable.
• Omit the ENO output variable in structured text. The ENO output variable is not required in structured
text because the execution condition for the next instruction is determined by the operation sequence.
Additional Information Additional information on the function of the instruction is provided. This includes related instruc-
tions and helpful information for application of the instruction.
Precautions for Cor-
rect Use
Precautions for application of the instruction are given. The conditions under which errors occur for
the instruction are also given here.
Sample Programming Short samples of how to use the instruction in an application program are provided. The ladder dia-
gram and ST for the same process are shown.
Common Variables
EN
Name Meaning I/O Description Data type Valid range Default
EN Enable (Execu-
tion Condition)
Input
TRUE: Instruction is executed.
*
FALSE: Instruction is not executed.
BOOL TRUE or
FALSE
TRUE
ENO
Name Meaning I/O Description Data type Valid range Default
ENO Enable Output Output TRUE: Normal end.*
FALSE: Error end, execution in
progress, or execution
condition not met.
BOOL TRUE or
FALSE
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