Mitsubishi Electric MELSEC FX3U - FNC125 - LOGE; Floating Point Natural Logarithm

532
FX3G/FX3U/FX3UC 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 DLOGEP)
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
XYMTCSD
 .b KnX KnY KnM KnS T C D R U\G VZModifyKH E "  "P
33 3 3 3
33 3 3
P
FNC 125
LOGE
D
−
−
Mnemonic Operation Condition
16-bit Instruction
DLOGE
DLOGEP
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