Large Display Temperature Meters
Instruction Manual
38
Isolated 4-20 mA Output Transmitter Option
The Digital Temperature Meter can be equipped with an optional isolated 4-20
mA output transmitter that can be programmed to produce a 4-20 mA signal for
virtually any temperature span displayed. For best performance, a 500 count
span is recommended between the 4 and 20 mA outputs. (Ex. 0.0
°
C = 4 mA,
50.0
°
C = 20 mA).
Figure 9 and Figure 10 on page 28 show the 4-20 mA output signal being
powered from the Digital Temperature Meter’s internal 24V power supply (AC
powered meters only) and by an external power supply.
To program the 4-20 mA output, a temperature display is programmed to
produce the 4 mA signal. Another temperature display, (higher or lower than the
one set for the 4 mA point), is programmed to produce the 20 mA signal. The
output will be linear as the temperature changes from the 4 mA setting to the 20
mA setting.
Example
: If the 4 mA point is set for 0
°
, and the 20 mA point is set for 1000
°
, the
output will be 6 mA when the temperature display reads 125
°
.
Note
: The 4-20 mA output is driven by the number been displayed. It doesn’t
adjust itself if the temperature scale is changed.
4-20 mA Output Programming (
output
)
Press
ENTER,
then press
ENTER
again when the
output (
output
) menu appears.
output
Set the display for the value at which 4 mA is produced
The green LED labeled “
4
” will be on indicating the meter is
ready to accept the value at which 4 mA is produced. After
the display corresponding to 4 mA is accepted, an LED
labeled “
20
” turns on. For instructions, see
Five Basic Digit/Display-Setting
Instructions on page 31.
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final
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Set the display for value at which 20 mA is produced
The green LED labeled “
20
” will now be on indicating the
meter is ready to accept the value at which 20 mA is
produced. Program this value in the same fashion as was
done above.
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final
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4-20 mA Output Programming Confirmation
The values that have been programmed to produce the 4 and 20 mA outputs can
be quickly checked to make sure they are the desired values. To do this, access
the
outPut
routine by pressing
ENTER,
and then pressing
ENTER
again when
outPut
appears.
The green “
4
” LED illuminates indicating the meter is displaying the value at
which it will produce a 4 mA output. Confirm that this is the desired value. Press
ENTER
, the green “
20
” LED illuminates indicating the meter is displaying the
value at which it will produce a 20 mA output. Confirm that this is the desired
value. Press
ENTER
(within 3 seconds) before the entire display stops flashing
and the meter returns to indication mode.
