6. Calibration Instructions
The TT820D comes factory calibrated. If you need to re-calibrate the unit, two
options are available. The first one is the “ One Point Calibration ” and the second
one is the “ Advanced Calibration “.
One Point Calibration
In some cases, a single point calibration is sufficient especially when a process is at
a fixed set point.
1. With a temperature standard, verify the correct process temperature and
compare it to the TT820D reading.
2. With the “ UP ” and “ DW “ push buttons, located on the front of the
TT820D transmitter, adjust current output to the value read by the standard.
Advanced Calibration
To perform the “ Advanced Calibration ” you will need :
•
The MIST TT820D Programming Kit. ( ordered separatly )
• A milliamp indicator or a loop-powered calibrator.
• A temperature bath.
•
A standard reference temperature sensor.
•
Test leads
3
2
4-20 mA
Indicator
TT820D
Communication
Interface
AC Adapter
110V AC
RS232
1. Connect the TT820D as per the wiring diagram shown above.
2. Start the MIST T/C software.
3. Go in the Programming section of the software by clicking on the
“ Program ” button.
4. Set the temperature bath to the minimum range of the TT820D transmitter
( Ex.: 0
o
C = 4 mA )
5. With the temperature standard, verify the bath temperature and enter the
value in the “ First Point” text box located in the “ 2 Points Calibration ”
section of the “ Programming ” window.
6. Immerse the TT820D probe in the temperature bath and wait for the
output stabilizes.
7. Click on the “ Read ” button associated to the “ First Point ” calibration.
+i
-i
Tx
Rx
+
_
Tx
Rx
E
F
G
H
D
C
+TC
-TC
2.448 ”
[ 62.18 ]
2.52 ”
[ 64.00 ]
.670 ”
[ 17.02 ]
.490 ”
[ 12.45 ]
4. Dimensions
+
_
Power Supply
12-36V DC
4-20 mA
Indicator
The diagram above represents the connection method to provide the 4-20 mA with
a current loop output. The connections should be made in the following order :
1. Connect the Thermocouple to the « C » and « D » terminals on the TT820D.
Be sure to respect the polarity of the thermocouple ( C to Neg. D To Pos. )
otherwise the output will not correspond to the right reading.
2. Connect the positive side of the power supply ( 12-36 VDC ) to the « E »
terminal on the TT820D.
3. Connect the positive side of the current loop indicator to the « F » terminal
on the TT820D.
4. Connect the negative side of the current loop indicator to the negative side
of the power supply ( 12-36 VDC ).
Note :
i ) It takes about 30 seconds, due to the filtering features, before the output
signal stabilizes to its value.
ii ) The indicator could be replaced by a controller, a data logger, etc.
In any case, be sure to respect the maximum load allowed on the loop,
given by :
Rmax. = [ ( Vsupply – 12V ) / 20mA ]
5. Electrical Connections
TT820D
E
F
D
C
+TC
-TC
