Schneider Electric 890USE17700 - Manual (Page 184)

Glossary
184 890USE17700 April 2004
process image A part of the NIM firmware that serves as a real-time data area for the data exchange
process. The process image includes an input buffer that contains current data and
status information from the island bus and an output buffer that contains the current
outputs for the island bus, from the fieldbus master.
producer/
consumer model In networks that observe the producer/consumer model, data packets are identified
according to their data content rather than by their physical location. All nodes listen
on the network and consume those data packets that have appropriate identifiers.
Profibus DP Profibus Decentralized Peripheral. An open bus system that uses an electrical
network based on a shielded two-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.
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 one
complete cycle. For a sine wave, the rms value is 0.707 times the peak value.
role name A customer-driven, unique logical personal identifier for an Ethernet Modbus TCP/
IP NIM. A role name is created either as a combination of a numeric rotary switch
setting and the STB NIP 2212 part number or by modifying text on the Configure
Role Name web page. After the STB NIP 2212 is configured with a valid role name,
the DHCP server will use it to identify the island at power up.
RTD resistive temperature detect. An RTD device is a temperature transducer composed
of conductive wire elements typically made of platinum, nickel, copper, or nickel-
iron. An RTD device provides a variable resistance across a specified temperature
range.
R