GE DigitalFlow DF868, Service Manual

Page: 10 / 68

Chapter 1. Calibration
2 DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Service Manual
1.3 Calibrating the Analog Outputs
Every Model DF868 flowmeter includes two built-in analog outputs (A and B) at terminal block
I/O
, which is
designated as
Slot 0
. Both the zero-point and full-scale values for each output must be calibrated. After calibrating the
outputs, which have a resolution of 5.0

A (0.03% full scale), their linearity should be tested.
Note:
The zero point of the analog output may be set for either 0 mA or 4 mA. However, the calibration procedure
always uses the 4 mA point, as the meter will extrapolate this value to obtain the 0 mA point.
Prepare for the calibration procedure by connecting an ammeter to analog output A of
Slot 0
, as shown in Figure 1
below. Refer to the menu map in Figure 6 on page 13.
Figure 1: Ammeter Connection (Output A)
Press the
[CAL]
key to enter the Calibration Program :
CALIBRATION
 
Press
[F1]
to calibrate
Slot 0
. (The option bar will include a slot listing for each
installed option card.)
Cal
last slot selected
SLOT0 SLOT1 SLOT2 SLOT3
Terminal Block I/O (Slot 0)
B
RTN
B
SIG
A
RTN
A
SIG
4 1
+ -
Ammeter