Yokogawa Standalone MW100 - Manual (Page 109)

App-7
IM MW100-17E
Appendix
1
2
3
App App
Index
Values per Modbus Registers (Measurement channel data and MATH
channel data)
The main module handles data on measurement channels as type Int16, and data on
MATH channels as type Int32. The Modbus register values of these data are shown in
the table below.
Value type Name/description of value Value per Modbus register
Int 32 Int 16 Float Bit *1
+Over +Over 2,147,450,879
(0x7fff 7fff)
32,767
(0x7fff) +Inf(0x7f80 0000) 0
Data value greater than the upper limit
–Over –Over –2,147,385,343
(0x80001 8001)
–32,767
(0x8001) –Inf(0xff80 0000) 0
Data value smaller than the lower limit
Skip Skip –2,147,319,806
(0x8002 8002)
–32,766
(0x8002) –NaN(0xff80
0002)
0
Channel disabled
No Channel No channels –2,147,254,269
(0x8003 8003)
–32,765
(0x8003) –NaN(0xff80
0003)
0
No channels exist
Error Error –2,147,188,732
(0x8004 8004)
–32,764
(0x8004) –NaN(0xff80
0004)
0
Error in computation of data value *2
Invalid Undefined –2,147,123,195
(0x8005 8005)
–32,763
(0x8005) –NaN(0xff80
0005)
0
Data value is undefined *3
Lack Computation omitted –2,147,057,658
(0x8006 8006)
–32,762
(0x8006) –NaN(0xff80
0006)
0
Computation not processed
Valid Data is valid Mantissa *4 Mantissa *4*5 Physical qty. 0, 1 *6
*1 The value of the bit alone is insufficient to determine whether it is a special value. Mode (18000’s, 38000’s) and other
information must also be used to determine whether it is a special value or other value.
*2 If the data to be computed or the computed result is NaN, an error occurs. Furthermore, data resulting in an error is
replaced with +Over or –Over according to the “Operation upon Computation Error” setting.
*3 After turning the power to the MW100 ON, data values are undefined (Invalid) until initial measurement and computation are
finished (until the first data of measurement and MATH channels is created).
*4 Only the mantissa of values can be acquired from Int 32 format data of measurement and MATH channels. Decimal place
information of some form must be acquired separately from the MW100 in order to convert to physical values.
*5 When the expressible range in the Int 16 type is exceeded, the value takes on the upper or lower limit for the data range.
Take care when you use Int 16 registers to handle MATH channel data. Let x and y denote the original data and the
corresponding values per Modbus registers respectively,
y=min (when x < min)
y=x (when min < x < max)
y=max (when max < x)
where min=–32,768 (0x8000), max=32767 (0x7fff)
*6 The value is 0 (Off) when the corresponding measurement channel data or MATH channel data is zero, and 1 (On) when
data is not zero.
Note
This is an example of acquiring decimal place information.
• For measurement channels
• In the Web browser’s Input Range Setting screen, check the values in the Decimal
columns under Scale (when scaling is not used, the decimal place of the value in the
Span column).
• Acquire channel information using an SR command query of the MW100-specific
communication service.
• Output measurement channels using the FD command of the MW100-specific
communication service, then check the “Exponent” value.
• For MATH channels
• In the Web browser’s “Expression Settings” screen, check the value in the Decimal
column under Span.
• Acquire channel information using an SO command query of the MW100-specific
communication service.
• Output MATH channels using the FD command of the MW100-specific communication
service, then check the “Exponent” value.
Appendix 2 Modbus Protocol