Siemens SITRANS P500, Руководство по эксплуатации, Страница: 232 / 238

Glossary
SITRANS P500 with HART
232
Operating Instructions, 12/2014, A5E02344528-09
Final controlling element
Converter that converts electrical signals into mechanical or other non-electric variables.
Firmware
Firmware (FW) is software that is embedded on a chip in electronic devices – in contrast to
software which is saved on hard disks, 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 is a simple form of modulation, where the digital values 0 and 1
modulate the actual current signal by means of 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 fieldbusses. 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.
Non-volatile memory
→
EEPROM
Risk
Combination of the probability of damage occurring and the extent of the damage.
Safety function
Defined function executed by a safety-instrumented system with the objective of attaining or
maintaining a safe system state by taking a defined hazardous incident into account.