12
7.2.6 Sensor fault analogue indication ‘FAuLt’
The sensor fault analogue indication function appears
in the menu when the transmitter is configured for a
resistance thermometer or a thermocouple input.
When a fault is detected the transmitter’s 4/20mA
output current is set to the specified under or over
range fault value and the transmitter’s digital display
flashes. One of three fault currents may be selected,
or the fault indication may be turned off.
Irrespective of how the function is set the transmitter
display will flash when a sensor fault is detected.
Selected
Output
Transmitter
fault current
current
display
‘oFF’
No fault indication
Flashes
‘dn3.6’
3.6mA
*
Flashes
‘dn3.8’
3.8mA
Flashes
‘uP 21’
21.0mA
Flashes
*
Not recommended when HART
communication is used.
The ‘FAuLt’ function may be selected from within the
configuration menu by operating the
▼
or
▲
button.
To enter the function press
P
which will reveal the
existing setting which may be changed using the
▼
or
▲
button. When set as required, press
E
to enter
the selection and return to the ‘FAuLT’ prompt in the
configuration menu.
The typical detection thresholds and approximate
response times are:
Thermocouple
> 5k
Ω
10 sec
RTD sensor < 5
Ω
>500
Ω
1 sec
RTD sense leads
> 50
Ω
10 sec
In the time between a fault developing in an RTD
sense lead or a thermocouple and the fault being
detected, the transmitter output and display may drift
from the last correct measured value.
7.2.7 Configuration of 4/20mA output ‘CAL’
This function defines the relationship between the
transmitter input and the 4/20mA output current.
‘ZEro’ defines the transmitter input at which the
output is 4mA and ‘SPAn’ defines the input at which
the output is 20mA.
This function does not affect the transmitter display
which is fixed for thermocouple and resistance
thermometer inputs and adjusted via the ‘in-Lo’ and
‘in-Hi’ functions for resistance and voltage inputs.
The ‘CAL’ function may be selected from within the
menu by operating the
▼
or
▲
button. To enter the
function press
P
which will display the ‘ZEro’ function
in the sub-menu, pressing
P
again will reveal the
existing transmitter input at which the transmitter
output current is 4mA. Input is shown in units which
depend upon how the transmitter input ‘InPut’ and
display ‘dEG’ have been configured, as shown
below:
Configured Input
transmitter input shown as
Thermocouple
o
C,
o
F, K or r
Resistance thermometer
o
C,
o
F, K or r
Voltage
mV
Resistance
Ohms
The input, at which the transmitter output current is
4mA, may be changed using the
▼
or
▲
button to
adjust the flashing digit and the
P
button to move
control to the next digit. When the required input has
been selected, press
E
to enter the selection and
return to the ‘ZEro’ prompt.
The ‘SPAn’ function, which defines the input at which
the transmitter current output is 20mA, may be
selected from within the sub-menu by operating
either the
▼
or
▲
button. To enter the function press
P
which will reveal the existing transmitter input at
which the transmitter output current is 20mA. Again
the input will be shown in units which depend upon
how the transmitter has been configured.
The input, at which the transmitter output current is
20mA, may be changed using the
▼
or
▲
button to
adjust the flashing digit and the
P
button to move
control to the next digit. When the required input has
been selected, press
E
to enter the selection and
return to the ‘SPAn’ prompt.
Note:
When configured for a voltage input, operating
the
P
button when the 0.1mV digit is flashing in the
‘Zero’ or ‘SPAn’ sub-menus increases the input
resolution to 0.01mV which is indicated by the display
colon being activated. When the required input has
been selected, pressing
E
enters the selection and
returns the transmitter to the ‘ZEro’ or ‘SPAn’ prompt
in the sub-menu.
If, when configured for a voltage or resistance input
the displayed decimal point has been set to
autorange, it may be necessary to manually position
the decimal point before adjusting ‘ZEro’ or ‘SPAn’.
This can be achieved by repeatedly operating the
P
button until the activated decimal point flashes, the
decimal point can then be positioned using either the
▼
or
▲
button. Pressing the
P
button again will
return control to one of the digits.