TOTALIZATION AND FLOW DATA FORMAT:
The EtherMeter was designed in such a way as to simplify and compress the formatting of all
reported data. As shown in the previous charts, no floating point or 64-bit registers are implemented
in the N7 registers, as all data is represented internally as 32-bit long integers (signed or unsigned)
and 16-bit signed integers.
In order to achieve a high level of simplicity and prevent integer overflows, separate exponential
scale factors and multipliers are provided in certain N7 registers.
If fully-scaled totalization data is desired, then 64-bit data processing may be required by the DF1
master polling PLC or computer. In most instances, however, 32-bit data manipulation will suffice.
TOTALIZATION HELPER FORMULAS:
The following calculations are examples helper formulas that may be implemented within the
master. When deciding whether to use 64-bit versus 32-bit data manipulation routines at the
master, it is recommended that the user factor in the largest expected meter totalization value
(meter-specific), and consider that the largest possible 32-bit unsigned long integer is
4,294,967,295.
Meter 1 Actual Total = ( [METER 1 TOTAL UNSCALED] x [10
[METER 1 EXPONENT]
] )
+ ( [ROLLOVERS METER 1] x [10
[METER 1 nDIGITS]
] x [10
[METER 1 EXPONENT]
] )
= ( [N7:0,1] x [10
[N7:20]
] ) + ( [N7:8] x [10
[N7:18]
] x [10
[N7:20]
] )
Meter 2 Actual Total = ( [METER 2 TOTAL UNSCALED] x [10
[METER 2 EXPONENT]
] )
+ ( [ROLLOVERS METER 2] x [10
[METER 2 nDIGITS]
] x [10
[METER 2 EXPONENT]
] )
= ( [N7:2,3] x [10
[N7:21]
] ) + ( [N7:9] x [10
[N7:19]
] x [10
[N7:21]
] )
FLOW RATE HELPER FORMULAS:
The following are possible flow rate helper formulas that may be implemented within a DF1 master
polling PLC or computer:
Meter 1 Actual Flow = [FLOW 1] / 1000
= [N7:4,5] / 1000
Meter 2 Actual Flow = [FLOW 2] / 1000
= [N7:6,7] / 1000
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