486
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
18 Floating Point – FNC110 to FNC139
18.13 FNC125 – LOGE / Floating Point Natural Logarithm
18.13 FNC125 – LOGE / Floating Point Natural Logarithm
Outline
This instruction executes the natural logarithm operation.
→
For handling of floating point, refer to Subsection 5.1.3.
1. Instruction format
2. Set data
3. Applicable devices
Explanation of function and operation
1. 32-bit operation (DLOGE and DLOGP)
Natural logarithm [logarithm whose base is "e (2.71828)"] of [
+1,
] is calculated, and the operation
result is stored to [
+1,
]. A real number can be directly specified as
.
• Only a positive value can be set in [
+1,
]. (The natural logarithm operation cannot be executed
for a negative value.)
Errors
An operation error is caused in the following cases; The error flag M8067 turns ON, and the error code is
stored in D8067.
• When a negative value is specified in
(error code: K6706)
• When "0" is specified in
(error code: K6706)
Operand Type
Description
Data Type
Head device number storing binary floating point data used in the natural
logarithm operation
Real number (binary)
Head device number storing the operation result
Oper-
and
Type
Bit Devices
Word Devices
Others
System User
Digit Specification
System User
Special
Unit
Index
Con-
stant
Real
Number
Charac-
ter String
Pointer
X Y M T C S D
.b KnX KnY KnM KnS
T
C
D
R U
\G
V
Z Modify K
H
E
"
"
P
3 3
3
3
3
3 3
3
3
P
FNC 125
LOGE
D
−
−
Mnemonic
Operation Condition
16-bit Instruction
DCMP
DCMPP
Mnemonic
Operation Condition
32-bit Instruction
9 steps
Continuous
Operation
Pulse (Single)
Operation
S
D
S
D
S
S
D
D
S
Command
input
FNC125
DLOGE
S
D
+1
Binary floating point
(real number)
+1
Binary floating point
(real number)
log
e
S
S
D
D
S
S
S
S