Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 345)

Publication 1404-UM001F-EN-P - November 2009 345
Glossary
discrete input
This is a Modbus mapped location used for reading bit length data.
These bits typically reflect the value of the discrete inputs.
Powermonitor 3000 units do not support this data type.
exception reply
This is the Reply Packet for a Modbus Command that was
unsuccessful in operation.
frequency
The number of recurrences of a periodic phenomenon in a unit of
time. In electrical terms, frequency is specified as so many Hertz (Hz)
where one Hz equals one cycle per second.
function code
Function byte: second byte of any Modbus Command packet.
holding register
This is a Modbus mapped location used for reading the writing word
length data. For a power monitor slave device, the locations are
defined by the Modbus Memory Map.
horsepower (hp)
A unit of power, or the capacity of a mechanism to do work. It is
equivalent to raising 33,000 pounds one foot in one minute. One
horsepower equals 746 watts.
impedance
The total opposition (that is, resistance and reactance) a circuit offers
to the flow of alternating current at a given frequency. It is measured
in ohms.
induction motor
An alternating current motor in which the primary winding (usually
the stator) is connected to the power source and induces a current
into a secondary (usually the rotor).
inductor
A device consisting of one or more windings with or without a
magnetic core. Motors are largely inductive.