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Appendix E - MODBUS Communications
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0 = units (amps squared)
3 = kilo units
6 = mega units
Connection Type (MODBUS register 1720): The meter service connection type. A 3-wire Delta
connection returns 30, while a 4-wire Wye returns 40.
Demand Method (MODBUS register 1721): A bit field indicating the demand methods
configured in the meter.
(MSB)-> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E S <-(LSB)
Where: E is the External Demand Interval Sync Enabled bit (1 = external demand sync, 0 =
internal sync).
S is the Sliding Window Demand indicator (1 = sliding window, 0 = fixed window)
Demand Interval (MODBUS register 1722): The JEMStar's demand interval length in minutes.
Demand Subinterval (MODBUS register 1723): The JEMStar's demand subinterval length in
minutes.
Number of Normal Display Registers (MODBUS register 1724): The number of display registers
(max. 50) currently configured in the Normal display list.
Number of Alternate Display Registers (MODBUS register 1725): The number of display
registers (max. 50) currently configured in the Alternate display list.
Number of Internal Display Registers (MODBUS register 1726): The number of display registers
(max. 50) currently configured in the Internal display list.
Number of Load Profile Channels (MODBUS register 1727): The number of Load Profile pulse
channels (max. 12) currently configured in the meter.
MODBUS Register Formats
These extended MODBUS holding registers come in a variety of formats. These formats are described
here.
Int
The Int type is a signed 16-bit integer number. It is the basic MODBUS register.
Long
The Long is two MODBUS registers sent consecutively to form a 32-bit value. The first register contains
the sign bit and the 15 most significant bits of the value. The second register contains the remaining 16
least significant bits.
Time
The Time format is three MODBUS registers sent consecutively to form a date-time group encoded thus:
Upper 8 bits
Lower 8 bits
First register
Month (1 - 12)
Day (1 - 31)
Second register
Year (0 - 199)
Hour (0 - 23)
Third register
Minute (0 - 59) Second (0 - 59)
E-23