Manual

Rockwell Automation Publication 1425-UM001A-EN-P - January 2012 37
Software Interface Chapter 3
Comments on PowerMonitor W250 Modbus Register Tables
The following sections provide comments on the Modbus register tables.
Energy Usage Data (Register 0…23)
These registers contain the raw, unscaled total consumed energy measured by the
PowerMonitor W250 unit. The scaling factors listed in the next section must be
applied to obtain energy values in the applicable engineering units of wH, VARh,
and VAh. The energy counter time-stamp indicates when the data is sent to the
gateway.
Energy usage data increments positive for energy consumed and negative for
energy generated.
Real, reactive, and apparent energy consumption values are stored as 32-bit
integer values using two Modbus registers. The lower register address contains
the high (most significant) word (MSW), the higher register contains the low
(least significant) word value (LSW).
See Scaling Factors
for information on scaling the raw energy values in these
registers.
Table 15 - Information for Table 14
Term Description Comments
NV Non-volatile Value is restored after a power cycle
V Volatile Value is not restored after a power cycle
S16 Signed 16-bit INT Range -32,768…32767
U16 Unsigned 16-bit INT Range 0…65,535
S32 Signed 32-bit INT Range -2,147,483,648…2,147,483,647
U32 Unsigned 32-bit INT Range 0…4,294,967,297
MSW Most Significant Word
LSW Least Significant Word
Table 16 - Energy Counters
0, 2, …22 1, 3, …23
MSW LSW