Spirax Sarco ILVA20 - Page 67

IM-P337- 6 9 EMM Issue 2
67
12.1.2 Floating Point Format
IEEE-754-1985 standard for 32-bit (single precision) floating point values are stored in adjacent registers
with the low 16 bits on an even address and the high 16 bits on the following odd address. The floating point
value is store in the registers as follows:
Register High 16 bits (Address XXX1) Low 16 bits (Address XXX0)
Byte 4 3 2 1
Bit 31 30..24 23 22..16 15..8 7..0
IEEE-754 Sign Exponent (8 bits) Mantissa (23 bits factional part)
The floating point value 1234.0 (sign, 0; exponent, 0x89, mantissa 0x1A4000) will have a low 16 bits of 0x4000
and high 16bits 0x449A. Both parts of the floating point value must be read in a single transfer to
ensure the correct value is read.
Deprecated Read Holding Registers
The following deprecated registers are supported for backwards compatibility with previous products:
Table 1 Register Groups
Register Functionality
40,001 to 40,009 Read flow meter values in metric units. DEPRECATED.
40,001 to 40,029 Read flow meter values in imperial units. DEPRECATED.
Table 2 Flow Meter Values
Address Parameter Units Notes
40,001 Total low 16 bits
kg
Tonne x 100
Total = (Total high x 65536) + Total low
40,002 Total high 16 bits
40,008 Energy low 16 bits
kWh
MWh x 100
Energy = (Energy high x 65 536) + Energy low
40,009 Energy high 16 bits
40,021 Total low 16 bits
lbs
Ton x 100
Total = (Total high x 65 536) + Total low
40,022 Total high 16 bits
40,028 Energy low 16 bits kBTU
40,029 Energy high 16 bits MBTU x 100 Energy = (Energy high x 65 536) + Energy low