Specifications

Glossary
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Profibus DP
Profibus Decentralized Peripheral. An open bus system that uses an electrical
network based on a shielded 2-wire line or an optical network based on a fiber-optic
cable. DP transmission allows for high-speed, cyclic exchange of data between the
controller CPU and the distributed I/O devices.
Q
QoS
(quality of service). The practice of assigning different priorities to traffic types for the
purpose of regulating data flow on the network. In an Industrial network, QoS can
help provide a predictable level of network performance.
R
reflex action
A simple, logical command function configured locally on an Island bus I/O module.
Reflex actions are executed by Island bus modules on data from various Island
locations, like input and output modules or the NIM. Examples of reflex actions
include compare and copy operations.
repeater
An interconnection device that extends the permissible length of a bus.
reverse polarity protection
Use of a diode in a circuit to protect against damage and unintended operation in the
event that the polarity of the applied power is accidentally reversed.
rms
root mean square. The effective value of an alternating current, corresponding to the
DC value that produces the same heating effect. The rms value is computed as the
square root of the average of the squares of the instantaneous amplitude for 1
complete cycle. For a sine wave, the rms value is 0.707 times the peak value.