Omron NJ-series User Manual page 371

8 CPU Unit Functions
You cannot specify an array, structure, or union.
The types of variables that you can specify are listed below.
System-defined variables
Semi-user-defined variables
User-defined vari-
ables
*1 The following variables cannot be used:
EN, ENO, P_Off, P_CY, P_First_RunMode, P_First_Run, and P_PRGER.
*2 In-out variables cannot be used.
 Condition Expressions
The condition of the change in the variable to detect is called the condition expression. There are
two types of condition expressions that you can select from. You specify a condition expression for
each variable.
• Change to TRUE
• Change to FALSE
Precautions for Correct Use Precautions for Correct Use
For example, we will assume the condition expression was set to a change to TRUE. Even if the
value of the specified variable is TRUE when differential monitoring is started, the status of the
value of the variable is not detected as a change to TRUE. The value of the variable must first
change to FALSE and then to TRUE to be considered as a change to TRUE.
When Conditions Are Evaluated and the Match Count
The condition for the specified variable is evaluated every primary period. The value of the variable
from the previous evaluation is compared with the value of the variable for the current evaluation. If
the value of the variable that matches the specified condition has changed, the count is incre-
mented.
• The number of times a condition match occurs is counted separately for each variable.
• The count values are reset to zero when differential monitoring is started.
• The count value for just one variable cannot be reset to zero.
Precautions for Correct Use Precautions for Correct Use
• Even if the value changes to match the condition expression more than one time within the
same primary period, the count will be incremented only once in each primary period.
• If the values of the variable are the same at the time of the previous and current evaluations,
the condition is not considered to be a match, even if the value changed between evaluations.
8-44
Type of variables
Global variables
Variables used in a program
Variables used in a function block
Variables used in a function
Specification
*1
Possible.
Possible.
Possible.
Possible.
*2
Possible.
Not possible.
NJ-series CPU Unit Software User's Manual (W501)