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Interpreting the PowerScout Registers – Data Scaling
The use of Modbus protocols limits the data registers to a maximum of 2 bytes (16 bits) or a maximum decimal
value of 65535. Modbus also requires that the values be integer values. To overcome these limitations some
measured (and stored) values have to be scaled to fit into the Modbus registers. To convert the raw data read
from the Modbus registers a scalar must be multiplied by the raw value. For this meter the scaling is:
Table 2: Data Scalar and Resolution of Modbus Values for Registers 44001 thru 44061
Register
kW/kWh Demand
44302
0
.00001
1
.001
2
.01
3
.1
4
1
5
10
≥6
100
For example, if the scalar value in register 44302 is set to 3 and the total true power for the system (kW) is
read from Modbus register 44003 (Offset 4002) and a value of 3465 is returned, the true system kW is
3465 X 0.1 = 346.5 kW.
A raw value of Apparent Power Factor from register 44015 might be 87. This would correspond to an actual
power factor of 87 X 0.01 = .87 PF
Additionally, some values (e.g., kilowatt-hours) may cover a dynamic range that is larger than 65535 and
require two Modbus registers. Any parameter in Table 1 that shows two registers (identified by the terms
"MSW" and "LSW") is such a wide-ranging parameter.
To correctly interpret the values found in these registers note that the number in the MSW (Most Significant
Word) register should be multiplied first by 65536. This number should be added the value found in the
corresponding LSW (Least Significant Word) register and then multiplied by the appropriate value from Table
2.
For example, assume that System Total True Energy (kWh) is desired and the value of 5013 is read from
register 44001 (LSW) and 13 is read from register 44002 (MSW) and that the Register 44064 Scalar is set to 3.
To calculate the total kWh recorded:
Multiply the MSW by 65536 → 13 X 65536 = 851968
Add the LSW → 851968 + 5013 = 856981
Multiply by the Table 2 Scalar of 0.1 → 856981 X 0.1 = 85698.1 kWh
Shop for Dent products online at:
kVAR/kVARh
kVA/kVAh
.00001
.00001
.001
.001
.01
.01
.1
.1
1
1
10
10
100
100
14
PowerMeterStore
www.
Power Factor
Amps
.01
0.01 A
.01
0.1
.01
0.1
.01
0.1
.01
1 A
.01
1
.01
1
1.877.766.5412
.com
Volts
0.1V
0.1
0.1
0.1
1 V
1
1
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