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16 SINGLE NUMBER VARIABLE FUNCTIONS
16.4 Calculating the Common Logarithm
16.4 Calculating the Common Logarithm
LOG(_E)
These functions output the operation result of the common logarithm (the logarithm whose base is 10) of an input value.
â– Descriptions, types, and data types
â– Operation processing
• These functions calculate the logarithm whose base is "10" of the REAL type data input to (s), and output from (d).
• These functions are expressed as follows when the input value is "A" and the output operation result is "B".
• A value input to (s) is the REAL type data value.
• Only a positive value can be set in (s). (The logarithm operation cannot be executed for a negative value).
• When the operation result is -0 or underflow occurs, the operation result is regarded as 0.
â– Operation result
1. Function without EN/ENO
The following table lists the operation results.
2. Function with EN/ENO
The following table lists the execution conditions and operation results.
*1 When FALSE is output from ENO, data output from (d) is undefined. In that case, modify a program so that the data output from (d) is
not used.
Ladder diagram Structured text
[Without EN/ENO] [With EN/ENO] [Without EN/ENO]
d:=LOG(s);
[With EN/ENO]
d:=LOG_E(EN,ENO,s);
Argument Description Type Data type
EN Execution condition (TRUE: Execution, FALSE: Stop) Input variable BOOL
s Input Input variable REAL
ENO Output condition (TRUE: Normal, FALSE: Abnormal) Output variable BOOL
d Output Output variable REAL
B=log
10
A
Operation result (d)
No operation error occurred Operation output value
An operation error occurred Indefinite value
Execution condition Operation result
EN ENO (d)
TRUE (Executes operation) TRUE (Operation error did not occur) Operation output value
FALSE (Operation error occurred)
*1
Indefinite value
FALSE (Stops operation) FALSE
*1
Indefinite value
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