Setra System Model Datum 2000 - Manual (Page 15)

15
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 mini-
mum 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.
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. Use the following formula to
calculate the pressure that corresponds to zero volts input (see examples).
Full scale pressure – offset pressure
SLOPE = —————————————————
Full scale voltage – offset voltage
OFFSET = Pressure ( @ voltage ) – (SLOPE x voltage)
PRESSURE = (SLOPE x VOLTAGE) + OFFSET
(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 con-
nected 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 refer-
ence 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.
1000 – 0
SLOPE = ————— = 200
5 – 0
OFFSET = 0 – 200 x 0 = 0