Rockwell Automation 1771-QB Linear Pos. - Manual (Page 174)

Glossary of Terms & Abbreviations
Appendix A
AĆ5
Reverse Motion: Axis movement in a negative direction along a coordinate
axis.
rms: Root mean square.
Servo Valve: A hydraulic valve assembly capable of controlling the linear
movement of a tool or workpiece.
Setpoint: A pre-defined position on the axis.
Shield: A conductive barrier that reduces the effect of electric and/or magnetic
fields.
Sign: The symbol or bit that distinguishes positive from negative numbers.
Signal: The event or electrical quantity that conveys information from one point
to another.
Significant Data: A digit that contributes to the precision of a value. The
number of significant digits begins with the one contributing the most
value (called the most significant digit) and ends with the digit
contributing the least value (called the least significant digit).
Summing Point: A point where signals are added algebraically.
Transducer: A device which receives energy in one form and supplies energy
in another; in a positioning system, transducers usually measure linear
displacement.
Trigger Conditions: The conditions which, when satisfied, cause a subsequent
motion segment to occur.
True: As related to PLC instructions, an enabled logic state.
Velocity: The target speed for the tool or workpiece to move along the axis.
Wiring Arm Terminal: Terminals used to connect to external power supplies,
discrete inputs and outputs, and interfaces.
Word: A sequence of bits treated as a unit.
Word Length: The number of bits in a word. The PLC word length is 16 bits.
Write: The process of loading information into memory, as in a block transfer
of data from the processor data table to an I/O module.
Write Operation: Sending a parameter block, setpoint block, motion block, or
command block from the programmable controller to the module.