Basic Functions Of Hart Communicator
Transmitter’ Hart communication function is achieved with the heart associated equipment such as hart and hand held terminal and host computers,
install with the relevant software that chapter describes transmitter hart function for the method how to implement hart functions into transmitters
please refer to the instruction manual of relevant hart equipment's such as hand-held terminal etc
Basic Hart Function
Hart functions are similar with the functions described in the transmitters with local keys the chapter will not describe
the following functions and again refer to set transmitters with the local keys for external operating environments and result.
1 ) Settings LRV and URV with the reference pressure
2 ) Settings LRV and URV without reference pressure
3 ) Zero adjustment zero pressure adjustment
4 ) Damping
5 ) Simulate constant current output
6 ) Selection of fault alarm current
7 ) Disabling keys and write-protection
8 ) Selection of output functions
9 ) Selection of display modes
10 ) Select pressure engineering units
At Hart communicator mood the constant current output in output in item 5) delectable between 3.55 and 23 milliampere. in item 6)
you can sit for fault alarm current value setting 3.6 mA for low alarm, 22.8 milliampere for high alarm default alarm value.
Set Current Limit
The fault current range at normal measurement condition is 3.84 to 20.5 milliampere normally the upper current limit is 20.5 milliampere
and lower current limit is 3.84 milliampere this function can modify the upper and lower current limit value the select able range of lower limit
value is 3.84 to 4 milliampere While the select able range of upper limit value is 22 To 20.5 milliampere
Sensor rain adjustable States transmitter a property between two adjustments point to obtain higher accuracy
The Adjustment point can be assigned to any value and sensor normal range for example for a 400kPa sensor
which typical measurements range is 50 to 300kPa, you can set the upper sensor in to 300KpA and lower sensor range to 50KPA
After setting sensor range you can trim its upper and lower value to obtain accurate range values trimming lower range
value will translate characteristic curve that is to say the upper range value will change with lower range value trimming
upper range value will not affect lower range value and will affect the gradient of characteristic curve
reference current
The resistance error of the 250 ohm standard visitor register through which 420 milliampere current flows effect measurements accuracy
with heart communicators the user can trim for milliampere and 20 Milli ampere current to compensate for accuracy loss resulting
from conversation current procedures are similar with domain of sensor upper and lower range value dreaming of 4 milliampere
current will shift current curve will return of 20mA will change the gradient of current curve
Return To Factory Setting
You can return transmitters to factory setting by using a return to factory setting a wale Rebel for Hart communicator select the parameters
which are to be e overwriting overwrite in in the menu of terminal follow the procedure below
1 ) Cancel current adjustment
2 ) Cancel Samsung zero adjustment position correction
3 ) Cancel pressure correction sensor range adjustment upper and lower limit trimming
4 ) Cancel my comments condition in parameters 0.3 and dumping display units alarm setting change in alarm current value and output over-current range
Sensor Damage
alarm current is used to indicate that sensors are damage not word fail to normally sense pressure and required immediate
replacement or maintenance at this point transmitter will output alarm current and alarm message can be viewed with handheld terminals
Limit Monitor
When the process pressure exceeds the statement maximum value in figure the transmitter will output standard upper limits current 20.5 milliampere
when the process, pressure does not return to normal pressure range within the defined response time transmitter will output alarm current alarm
current of 22.8 milliampere and minimum holding time is provided to ensure that operators find such problem and take my hairs accordingly when
the pressure return to normal value the current will return to normal value when the pressure briefly exceeds the defined value as shown in the above figure,
Transmitter will output standard upper limits current however because the over pressure duration does not reach response time the transmitter
will not output alarm current when the pressure is low then the lower pressure limits for more than response time the transmitter will output alarm
current again and pressure will return its normal value within minimum holding time at this point alarm current output is maintained after
the minimum holding time as the pressure will be within normal pressure range and current returns to normal measurements output .
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