DigitalFlow™ GC868 Service Manual (1 and 2-Channel)
1-4
Chapter 1. Calibration
If the linearity test readings are not within 5
A of the values listed in Table 1-1 above,
check the accuracy and wiring of the ammeter. Then, repeat the low and high end
calibrations. If the analog output still does not pass the linearity test, contact the
factory for assistance.
1.3.4.1
Procedure Options
You have completed calibration of the analog output. Do one of the following:
• To calibrate or test another output, press
[F4] (EXIT)
and return to Step 3 in
Accessing the Calibration Menu
on page 1-3.
• To calibrate/test additional slots, press
[F4] (EXIT)
twice and proceed to the
appropriate section.
• To leave the Calibration Menu, press
[F4] (EXIT)
three times.
1.4
Calibrating the
Analog Inputs
Analog inputs may be added to the Model GC868 flowmeter by installing an
Analog
Inputs Option Card
in one (or more) of the six expansion slots. The option card
contains two analog inputs, which are designated as A and B. Each of the inputs,
which may be either a 0/4-20 mA input or an RTD input, must be calibrated at both
the zero-point and full-scale values. After calibrating the inputs, their linearity should
be tested.
Calibration of the analog inputs requires the use of a calibrated current source. If an
independent calibrated current source is not available, one of the
Slot 0
analog
outputs may be used for the calibration. During the analog input calibration, the
Slot
0
analog output will supply the low reference, high reference, 4 mA and 20 mA
signals at the appropriate times.
Note:
If a
Slot 0
analog output is used to calibrate the analog inputs, make sure
that the
Slot 0
analog output calibration procedure has already been
completed.
Connect the
Slot 0
analog output(s) (or an independent calibrated current source)
to the analog input(s) on the option card, as shown in Figure 1-3 below. Refer to the
menu map in Figure 1-6 on page 1-12 as a guide.
90
18.400
18.000
100
20.000
20.000
* All ammeter readings should be ±0.005 mA
Table 1-1: Expected Ammeter Readings
% Full Scale
4-20 mA Scale* 0-20 mA Scale*