ONICON System-30 MODBUS BTU - Manual (Page 34)

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System-30 BTU Measurement System MODBUS RTU RS485 04/14 - 0583-1 / 18345
Page 34
4.7.3 Totalization, Resetting Tools, and Over-range & Rollover
A. Integer Register Totalization
Holding registers 40026 through 40061 are integer registers that provide
totalized energy, volume and mass flow data in a variety of engineering
units. The registers are organized into pairs or groups of 3.
The first (low order) register is limited to a range of 0 – 999. This register
rolls over to zero when the total value reaches 1,000. If the registers are in
a group of 3, the second register (middle order) is also limited to a range of
0 – 999. This register also rolls over when the register value reaches 1,000.
The second, or in the case of groups of 3, third, (high order) register is
scaled such that the smallest incremental value indicated is 1,000 times
greater than the preceeding register. An example of this is shown below.
Example - A group of 3 registers
Register Engineering units & Scaling Current Value
40026 kBtu (Btu x 1,000) 00500
40027 MBtu (Btu x 1,000,000) 00015
40028 GBtu (Btu x 1,000,000,000) 00111
Low order + middle order + high order = Btu Total = 111,015,500,000
or
kBtu Total = 111,015,500
Registers 40062 and 40063 provide totalization for the optional auxiliary
pulse input option of the System-30 BTU Meter. There are no engineering
units associated with these registers.
B. Floating Point Totalization
Registers 41003 through 41064 provide energy, volume and mass flow data in
32 bit single precision floating point format. The registers are organized into
pairs. Each pair must be concatenated according to IEEE 754.
Word order: Most significant value first, least significant value second. Byte
order within each word: Most significant byte first. Bit order within each
byte: Most significant bit first.
Registers 41063 and 41064 provide totalization for the optional auxiliary
pulse input option of the System-30 BTU Meter. There are no engineering
units associated with these registers.
C. Resetting Totals
Registers 40064 through 40068 or 41065 through 41069 are integer
registers that provide a mechanism to reset totals. Each reset register is
associated with a group of totalizing registers and will reset all of the