NBN 9320 User Manual - page 18
Interface 9320 TEDS Ready Indicator Manual Issue 2.4
18
Internal Calibration Procedure
1. Read and note the existing settings for gain and offset using the Internal Calibration Menu. If desired, the
settings for gain and offset may be reset to 1 and 0 respectively for convenience.
2. With the 9320 in normal operating mode, connect a mV/V calibration source to the sensor connector. A
precision simulator such as the Interface CX series is recommended. For the 5 mV/V range, a source of 3 or
4 mV/V is ideal. If a simulator is not available, another mV source may be used along with a precision DVM
to measure both the mV signal and excitation voltage in which case the input in units of mV/V is calculated
as the ratio. However, the simulator provides the most reliable and trouble-free method.
3. Take 9320 0 mV/V Reading and the 9320 4 mV/V Reading (using the preferred 4 mV/V as the example).
Find the net reading by subtracting the former from the later.
4. Calculate a new gain value per the formula
5. Set the New Gain value into the 9320 using the Internal Calibration Menu.
6. If desired, the offset may be adjusted. The offset value is not critical to the TEDS or
LiVE
or
tAbLE
methods of calibration. To adjust the offset parameter for a true zero reading at zero input, find the New
Offset value per the formula
7. Set the New Offset value into the 9320 using the Internal Calibration Menu.
Internal Calibration, Gain Example 1
Existing Gain: 1.007920
Simulator: CX-0404, 4 mV/V setting = 3.99992
9320 0 mV/V Reading: 0.0003
9320 4 mV/V Reading: 3.9996
New Gain = 1.007920 (3.99992) / (3.9996-0.0003) = 1.008076
Internal Calibration, Gain Example 2
Existing Gain: 1.008220
mV source DVM reading = 40.008 mV
Excitation DVM reading = 10.055 V
Calculated input = 40.008 / 10.055 = 3.9789 mV/V
9320 0 mV/V Reading: 0.0003
9320 4 mV/V Reading: 3.9861
New Gain = 1.0082200 (3.9789) / (3.9861-0.0003) = 1.006475
Input mV/V
New Gain = Existing Gain
(9320 4 mV/V Reading – 9320 0 mV/V
New Offset = Existing Offset + 9320 0 mV/V Reading