Calculating The Natural Logarithm - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

26.3

Calculating the Natural Logarithm

LN(_E)
RnPCPU
RnCPU RnENCPU
(Process)
These functions output the natural logarithm (logarithm with base e) of an input value.
Ladder, FBD/LD
[Without EN/ENO]
s d
Setting data
■Description, type, data type
Argument
EN
s (IN)
ENO
d
Processing details
■Operation processing
• These functions calculate the natural logarithm of the REAL/LREAL data type value input to (s), and output the operation
result from (d).
• When the input value is defined as A and the output value is defined as B, the relationship of A and B will be as follows:
B=log A
e
• Natural logarithm operation is performed with the base (e) defined as 2.71828.
■Operation result
1.
Function without EN/ENO
The operation processing is performed. The operation result is output from (d).
2.
Function with EN/ENO
The execution conditions and operation results will be as follows.
Execution condition
EN
TRUE (executed)
FALSE (not executed)
*1 If the value FALSE is output from ENO, the output data from (d) will be undefined. Create a program so that the undefined value will not
be used in operations.
Operation error
Error code Description
(SD0)
3405H The input value is negative.
26 SINGLE VARIABLE FUNCTIONS
1896
26.3 Calculating the Natural Logarithm
RnPCPU RnSFCPU RnSFCPU
(Redundant) (Standard) (Safety)
[With EN/ENO]
EN ENO
s
Description
Execution condition (TRUE: Executed, FALSE: Not executed)
Input
Output status (TRUE: Normal, FALSE: Abnormal)
Output
Operation result
ENO
TRUE
FALSE
Structured text
[Without EN/ENO]
d:=LN(s);
[With EN/ENO]
d:=LN_E(EN,ENO,s);
d
*1
Type Data type
Input variable BOOL
Input variable ANY_REAL
Output variable BOOL
Output variable ANY_REAL
(d)
Operation result output value
Undefined value