Siemens SITRANS TH400 Operating Instructions Manual page 57

Fault tolerance
Fault tolerance N means that a device can execute the intended task even when N faults
exist. The device fails to execute the intended function in case of N+1 faults.
Final controlling element
Converter that converts electrical signals into mechanical or other non-electrical variables.
Firmware
Firmware (FW) is software which is embedded in a chip in electronic devices – unlike
software that is stored on hard drives, CD ROMs, or other media. These days, firmware is
mostly stored in a flash memory or EEPROM.
Firmware usually contains the elementary functions for controlling the device, as well as
input and output routines.
Frequency shift keying
Frequency shift keying in a simple form of modulation in which the digital values 0 and 1 are
represented by two different frequencies.
Frequency Shift Keying (FSK)
Frequency shift keying
→
HART
HART (Highway Addressable Remote Transducer) is a standardized, widely used
communications system used to structure industrial fieldbuses. The communications system
provides digital communications for multiple participants (field devices) via a common
databus. HART is based especially on the equally widely used 4/20 mA standard for the
transfer of analog sensor signals. The cabling from existing older systems can be used
directly and both systems operated in parallel.
HART specifies several protocol levels in the OSI model. It facilitates the transfer of process
and diagnostics data and control signals between field devices and high-level control
systems. Standardized parameter sets can be used for the manufacture-independent
operation of all HART devices.
Typical applications include transmitters for measuring mechanical and electrical
dimensions.
IP
International Protection = international degree of protection
SITRANS TH400
Operating Instructions, 06/2010, A5E01018688-02
Glossary
57