Mitsubishi Electric M800VW Series Programming Manual page 421

M800V/M80V Series PLC Programming Manual (1/2)
8 Function Instructions
8.11 Special Function Instructions
LOG, LOGP: Natural logarithm operation on floating-point data (single precision)
Setting
Bit devices
data
X Y M L F
S
D
△ : This is not available with ST.
[Instruction symbol] [Execution condition]
LOG
LOGP
 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
LOG
 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+1 S
Log (
32-bit floating-point real
number
 Only positive values can be designated by (S). (Operation cannot be performed with negative numbers.)
 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".
 Operation errors
 In the following cases, an arithmetic error occurs, the error flag (SM0) turns ON, and an error code is stored at SD0.
- The value designated by (S) is a negative number. (Error code: 34)
- The value designated by (S) is "0". (Error code: 34)
- The designated device value is not within the following range. (Error code: 35)
-126
0, 2 ≤ | Designated device value | < 2
- The designated device value is "-0", unnormalized number, nonnumeric, or ± ∞ . (Error code: 35)
- The operation result exceeds the following range. (When an overflow occurs) (Error code: 36)
| Operation result | < 2
IB-1501667-B
Usable devices
B SB T SM V T C
○ ○
○ ○
Command
Command
Meaning
D+1 D
)
32-bit floating-point real
number
128
128
Con-
Word devices
stant
D R/ZR W SW SD Z
○ ○ ○ ○ ○ △
○ ○ ○ ○ ○ △
400
Digit
Pointer designa- Index
tion
E P
○
○
indicates the sign "LOG".
S D
P S D
Data type
Real number