Yaskawa Ladder Works Programming Manual - Manual (Page 218)

A-6
3. Application to ladder program
The use of Expression in the ladder program is divided into three kinds of the following.
① Conditional expression of IF instruction
② Conditional expression of WHILE instruction
③ Operational expression of EXPRESSION instruction
The use example is explained as follows.
① Conditional expression of IF instruction
The Expression is described in the conditional expression description area of the IF
instruction and the ELSE instruction. However, only Expression which outputs the result
of the bool type can be described. Therefore, the description of the Expression which
includes the substitution operator is not recognized.
ex）
MB000001 == true OK
MW00002 < 100 OK
MW00003 != MW00004 OK
MB000005 = false NG
MW00007 = MW00010 NG
② Conditional expression of WHILE instruction
The Expression is described in the conditional expression description area of the WHILE
instruction. However, only Expression which outputs the result of the bool type can be
described. Therefore, the description of the Expression which includes the substitution
operator is not recognized.
ex）Refer to the example of ①.
③ Operational expression of EXPRESSION instruction
The Expression is described in the conditional expression description area of the
EXPRESSION instruction. The operational expression can be described according to the
description rule of Expression. However, Expression which outputs the result of the
bool type cannot be described.
ex)
MB000010 = MB000001 && MB000005; OK
MB000011 = MB000010 == true; OK
MW00000 = (MW00001 + MW00005) / MW00004; OK