27
Values Requiring Two Registers
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, in Appendix D,
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 IV-1.
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
I/O Port Function
The PowerScout 3 has two configurable I/O ports, 1 and 2. Each port can be set to one of two functions,
input or output, but not to both functions at one time. The ports can be used for pulse input and output
counting, or for a relay device for remote control.
Pulse Input
Pulse input is used to count, accumulate and scale pulses received from non-DENT external pulse-
initiating meters such as gas, water, or other electrical meters. The PowerScout 3 can detect digital
signals (dry contacts) of minimum 10 milliseconds in duration. The green LED will stay on while the pins
are shorted together. When the port is used as an input, the green LED is lit when the port contacts
close due to an external device.
Pulse Output
Pulse output is used to generate pulses for external devices such as data loggers that can accept pulses
but do not have modbus capability. The PowerScout 3 can generate pulses based on accumulated
value(s) such as system kWh, but also system kVARh and system kVAh. When a pulse is generated by the
PowerScout, the orange and green LEDs both will briefly flash, otherwise they will remain dark.
The number of pulses outputted, matches the corresponding register raw value before the scalar is
applied. The raw pulse output is scaled by the same data scalar register (44602) as the modbus registers.
For example, when the data scalar is set to 3, each pulse will represent .1 kWh, .1kVAh and .1kVARh.
For system pulse output:
kWh pulse output – write 44001 into the pulse output configuration register.
kVAh pulse output – write 44011 into the pulse output configuration register.
kVARh pulse output – write 44008 into the pulse output configuration register.
TECH TIP
: When
reading two register
values, ViewPoint
automatically
calculates the total
value.
Summary of Contents for PowerScout 3
Page 19: ...15 Figure IV 1 Single Phase Two Wire N white L1 black L2 red L3 blue ...
Page 20: ...16 Figure IV 2 Single Phase Three Wire N white L1 black L2 red L3 blue ...
Page 21: ...17 Figure IV 3 Three Phase Three Wire Delta N white L1 black L2 red L3 blue ...
Page 22: ...18 Figure IV 4 Three Phase Four Wire Wye N white L1 black L2 red L3 blue ...
Page 23: ...19 Figure IV 5 Three Phase Four Wire Delta N white L1 black L2 red L3 blue ...
