Answer / ajith294

Hart Communicator (Highway Adreessable Remote Traseducer)
is a communication device, which we can used for the
configuration, such as the input range (LRV, URV, Units,
Damping), if the transmitter is temperaure, we can change
the senser ( Mv / Ohms),

And trim (Lower range trim, Upper range Trim and Zero trim.
but is not a standard to use a calibrator. we must use a
high sensitive test equpments ie mA reader (Multimeter) to
read the accurate output mA

Now a days the control valve positioner also having HART
Protocol, means we can configure and put the auto
calibration of valve throgh HART Communicator.

there is no need to calibrate a HART Communicator, it is
clearly showing the user manual provided by ROSEMOUNT.

Answer / waqar ahmed chishti

Heart communicator is a device which can sense the smart
series transmitters and also provide out put of TX and also
match it with supply of input throw this a TX can be
calibrated without multimeter and it will also adjust the
zero and span or TX with out touching the TX,Heart
communicator can also used as source to provide 4 to 20 ma
to check a loop,it also use to calibrate DVC positioner it
will provide 4 to 20 ma to calibrate positioner,

Answer / manohar chotrani

HART® Field Communications Protocol is widely recognized as
the industry standard for digitally enhanced 4-20 mA smart
instrument communication. The HART protocol provides a
uniquely backward compatible solution for smart instrument
communication as both 4- 20 mA analog and digital
communication signals are transmitted simultaneously on the
same wiring. HART provides many benefits promised by
fieldbus, while retaining the compatibility and familiarity
of existing 4-20 mA systems.

Analog + Digital Communication
For many years, the field communication standard used by
process automation equipment has been a milliampere (mA)
analog current signal. In most applications the milli
ampere signal varies within a range of 4-20 mA in
proportion to the process variable being represented.
Virtually all installed plant instrumentation systems use
this international standard to communicate process variable
information.Simultaneous Analog + Digital Communication

HART uses Frequency Shift Keying to encode digital
information on top of the 4-20 mA analog signal
HART Field Communications Protocol extends the 4-20 mA
standard to enhance communication with intelligent
measurement and control instrumentation. A major step in
the evolution of process control, the HART protocol is
fostering significant innovation in process instrumentation
capabilities. The enhanced communication characteristics of
this important technology are reflected in the protocol
name, HART which stands for “Highway Addressable Remote
Transducer”.
The HART protocol enables two-way digital communication
with smart instruments without disturbing the 4-20 mA
analog signal. Both the 4-20 mA analog and HART digital
communication signals can be transmitted simultaneously
over the same wiring. Primary variable and control signal
information is carried by the 4-20 mA (if desired), while
additional measurements, process parameters, device
configuration, calibration, and diagnostics information is
accessible through the HART protocol over the same wires at
the same time. Unlike other “open” digital communication
technologies for process instrumentation, HART is
compatible with existing systems.

Paper Details: company -- Hindustan Copper Limited post -- GET 2008 Date -- 03.08.2008 Dept.-- Electronics?Instrumentation Aptitude -- 70 Technical-- 80 Total Time -- 2hr 30min I have listed the question I could able to remember 1. BCD equivalent of 43 2. value of K for stability of a system from a given equation 3. transformer connection for darlington connection 4. damping of balastic galvanometer 5. advantage of chart-pen recorder over CRo 6. CRO - how to change bandwidth 7. questions on CRO construction 8. reverse saturation current of si diode 9. advantage of wire wound resistance over carbon resistance 10. core material for a small coil 11. max fanout-- TTL/ECL/CMOS/MOS 12. component of resistance of monolithic IC 13. functions of capacitors in multivibrators 14. to change a sawtooth signal into a square wave we use-- schmit trigger/ schottkey diode/ zener diode 15. relation b/w á & â in transistor ckt 16. function of SiO2 layer in fabrication 17. 3 questions on ODD MAN OUT

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