15
8.2 Calibrating the DATUM 2000™ using an external reference voltage
Connect the external reference to the meter to simulate the transducer or
transmitter using the connection instructions on pages 4-6. Then, follow the
calibration instructions on page 18. During calibration, short -IN to Ground, pin 7
and pin 9 (CH2: pin 13 and pin 15). Be sure to set the minimum voltage of the
calibrator to the same value as the minimum output voltage of the transducer.
Apply the voltage/current for the first pressure point and enter the pressure reading
desired. Now apply the voltage/current for the second pressure point and enter the
desired pressure reading.
8.3 Calibrating the DATUM 2000™ for a transducer using the internal
reference voltage
The DATUM 2000™ has a very stable internal reference voltage which can be used
for calibration if the above methods cannot be used.
For the first pressure point the +IN, -IN and ground should all be shorted together,
pin 6, pin 7,and pin 9 (CH2: pin 12, pin 13, and pin 15). Enter the pressure that
corresponds to zero volts input (see examples).
Slope
=
Full scale pressure - offset pressure
Full scale voltage - offset voltage
Offset
=
Pressure (@ voltage)-(Slope x voltage)
Pressure
=
(Slope x voltage) + offset
Slope
=
1000 - 0
= 200
5 - 0
Offset
=
0 - 2000 x 0
= 0
Pressure (@ 0)
=
200 x 0 + 0
= 0
Pressure (@ Ref)
=
200 x 2.4995 + 0
= 499.9
(Definition of offset: Offset pressure and offset voltage refers to the minimum
pressure input and voltage output of the transducer, e.g., a 0-5 volt output, 600-
1100 mbar transducer, the offset voltage is 0 and the offset pressure is 600.)
For the second pressure point, the -IN and ground should be shorted, pin 7 and pin
9 ( CH2: pin 13 and pin 15). The reference voltage (either contact of the 2 pin blue
connector located behind the terminal strip) should be connected to the +IN, pin 6
(CH2: pin 12). Enter the pressure that corresponds to this input voltage according
to the formula above; the value of the reference voltage is recorded on the serial
number label on the bottom of the DATUM 2000™.
1st Example:
A 1000 PSI transducer has no offset voltage and an output of 5 volts at 1000 psi.
The DATUM 2000™ has a reference voltage of 2.4995.
