Mitsubishi Electric MELSEC Q Series Programming Manual page 47

Floating-point data in a CPU module can be monitored by the monitoring function of the programming tool.
To express 0 in floating-point data, set all of the following bits to 0.
• Single-precision floating-point data: b0 to b31
• Double-precision floating-point data: b0 to b63
The setting range of floating decimal point data is as follows.
• Single-precision floating-point data: -2
• Double-precision floating-point data: -2
Do not specify -0 (when only the highest bit of the floating-point real number is 1) for floating-point data. (A
floating-point operation with -0 results an operation error.) For the following CPU modules, a floating-point
operation does not result an error since -0 is converted to 0 in a CPU module when -0 is specified.
• High Performance model QCPU in which the internal operation is set to double precision
setting of internal floating-point operation is double precision.)
• Universal model QCPU (QnUDVCPU and QnUDPVCPU only)
The following are the CPU modules in which the operation results an error when -0 is specified.
• Basic model QCPU
• High Performance model QCPU in which the internal operation is set to single precision
• Process CPU
• Redundant CPU
• Universal model QCPU (excluding QnUDVCPU and QnUDPVCPU)
• LCPU
*4
• FXCPU
*1 For operations when an overflow or underflow is occurred, or when a special value is input, refer to the following manuals.
QCPU (Q mode)/LCPU
 User's Manuals (Function Explanation, Program Fundamentals) for the CPU module used.
FXCPU
 User's manuals and Programming Manuals for the FXCPU used
*2 Switching between single precision and double precision of the internal floating-point operation is set in the PLC system of the PLC
parameter. For single precision and double precision of floating point operation, refer to the User's Manual (Function Explanation,
Program Fundamentals) for the CPU module used.
*3 The floating point operation is supported with the Basic model QCPU with a serial number whose first five digits are '04122' or higher.
*4 Only the FX , FX , FX
2N 2NC 3S
128
1024
*3
, FX , FX , FX , and FX
3G 3GC 3U 3UC
*1
-126 -126
< Device data  -2
, 0, 2
-1022
< Device data  -2
, 0, 2
support floating point operations.
128
 Device data < 2
-1022 1024
 Device data < 2
*2
(The default
*2
4 PROGRAM CONFIGURATION
4.4 Method for Specifying Data
4
45