Rockwell Automation 1771-QB Linear Pos. - Manual (Page 171)

Glossary of Terms & Abbreviations
Appendix A
AĆ2
Circulations: A digital process that involves re-triggering an interrogation
pulse a fixed number of times by the return pulse, to provide more
counting time for digital counter circuitry, thus improving resolution
from a linear displacement transducer system. The on time of the digital
interface electronics pulse duration output is multiplied by a specified
factor. Circulation and recirculation are sometimes used
interchangeably.
Clear: To erase the contents of a storage device and replace them with zeros.
Closed-Loop: A signal path that compares its output with desired values to
regulate system behavior.
Control Loop: A closed-loop that controls the movement of a tool or workpiece
along an axis. (The module has two control loops.)
Current Sink: A signal sending device that shunts current to ground.
Current Source: A signal sending device that generates positive current.
D/A: Digital to analog convertor.
Data Table: The part of programmable logic controller memory that contains
I/O values and files. The data table is where you monitor, manipulate,
and change data to control your system.
Deceleration: The rate at which the speed of axis motion decreases.
Derivative Control: The component that causes an output signal to change as a
function of the rate of change of the error signal. Derivative control
helps to stabilize the axis movement by opposing changes in positioning
error.
Digital: Representation of data in discrete numerical form.
Digital to Analog Conversion: Production of an analog signal whose
instantaneous current or voltage is proportional to the value of the
digital input.
DIP: Dual in-line package.
Fault: Any malfunction that interferes with normal operation.
Feedback: The signal or data transmitted to the programmable logic controller
from a controlled machine to show the machine’s response to the
command signal.
Feedback Device: An element of a control system (e.g., a transducer) that
converts linear motion to an electrical signal for comparison with the
command signal.