V
ALUES
R
EQUIRING
T
WO
R
EGISTERS
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 the
Modbus Register Assignment
tables that shows
two registers (identified by the terms MSW (Most Significant Word) and LSW (Least Significant Word))
are examples of this wide-ranging parameter.
To interpret the values contained in these registers, the steps are:
1)
Multiply the MSW register by 65536.
2)
Add the result to the value found in the corresponding LSW register.
3)
Multiply the result by the appropriate scalar value from Table I-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 44602 data scalar is set to 3.
To calculate the total kWh recorded:
Multiply the MSW by 65536: 13 X 65536 = 851968
Add the LSW: 5013 = 856981
Multiply by the scalar 3 value of 0.1: 856981 X 0.1 = 85698.1 kWh
D
EVICE
R
EGISTERS
Modbus
Offset
Register
Description
44201
4200
Model Number 1
st
2 bytes
Model Name 10 bytes (ASCII Alpha-Numeric)
44202
4201
Model 2
“
44203
4202
Model 3
“
44204
4203
Model 4
“
44205
4204
Model Number last 2 bytes
“
44206
4205
Serial Number 1
st
2 bytes
Serial Number 10 bytes (ASCII Alpha-Numeric)
44207
4206
Serial 2
“
44208
4207
Serial 3
“
44209
4208
Serial 4
“
44210
4209
Serial Number last 2 bytes
“
44511
4510
Hardware ID
Hardware revisions.
D
ID
Y
OU
K
NOW
?
When reading two
register values,
ViewPoint
automatically
calculates the total
value.
64
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