M800V/M80V Series PLC Programming Manual (1/2)
8 Function Instructions
8.11 Special Function Instructions
LOGD, LOGDP: Natural logarithm operation on floating-point data (double precision)
Setting
Bit devices
data
X
Y
M
L
F
S
D
[Instruction symbol] [Execution condition]
LOGD
LOGDP
Setting data
Setting data
Data for which the natural logarithm is obtained or the first number of the device
S
where data is stored.
D
The first number of the device to store the operation result.
Functions
LOGD
Returns the natural logarithm with (e) as the base of the value designated by (S), and stores the operation result in the
device number designated by (D).
S+3
S+2
S+1 S
Log
(
64-bit floating-point real
number
Only positive values can be designated by (S). (Operation cannot be performed with negative numbers.)
When the operation results in "-0" or an underflow occurs, the operation result is processed as "0".
When setting input values from programming tools, rounding errors may occur.
For precautions when setting input values from programming tools, refer to "6.3.4 Single/Double-Precision Real Number
Data".
IB-1501667-B
Usable devices
B SB
T SM V
T
C
○
○
○
○
Command
Command
Meaning
D+3
D+2
D+1
D
)
64-bit floating-point real
number
Con-
Word devices
stant
D
R/ZR W SW SD
Z
○
○
○
○
○
○
○
○
○
○
402
Digit
Pointer
designa-
Index
tion
E
P
○
○
indicates the sign "LOGD".
S
D
P
S
D
Data type
Real number