4.a.4 INTERNAL 15-SEGMENT LINEARIZATION
For an input signal derived from a nonlinear transducer, an internal "look-up" table
can be created.* This table will be automatically reloaded on every powerup. The
purpose of such a table is to linearize the signal in question, to "bend" its charac-
teristic curves to achieve at least approximately "straight-line" performance.
You will set up a linearization table for the analog input by entering a ZERO ("MINI-
MUM") POINT and up to 15 subsequent LINEARIZATION POINTS. These points
will define up to 15 segments of the ideal linear output for that measurement sig-
nal. The more segments you specify, the greater the overall linearity. You can
load numeric points directly into the linearization table, or you can set up the table
by "forcing" a sequence of inputs to read desired measurement values ("out-
puts").
4.a.5 CALCULATED CALIBRATION
A conditioner can also be calibrated by directly entering an appropriate ZERO
OFFSET ("b" term) and an appropriate SCALING FACTOR ("m" coefficient) of the
desired precision (decimal-point location).
This technique is useful for some conditioners, but not for others. With the Model
3570 DC Strain Gage Conditioner, for example, it is a very convenient method
when both the "mV/V" sensitivity and the corresponding full-scale rating of the
transducer are accurately known. For the Model 3578 AC Strain Gage Condi-
tioner, on the other hand, it SHOULD NOT BE USED AT ALL.
For the Model 3540 Frequency Conditioner or Model 3560 Voltage Condi-
tioner, you can use "calculated" calibration if the unit is being used to measure
frequency or voltage itself. Here, all you need to do is to enter an appropriate
SCALING FACTOR of the desired precision.
For the Model 3510 Thermocouple Conditioner or Model 3530 LVDT Condi-
tioner, "calculated" calibration is only useful if you want to transfer the calibration
of one unit to another unit that has the same transducer/cabling system.
When calibrating a conditioner in this way, you should keep in mind that the
resulting accuracy is limited to either the stated "initial offset" accuracy or the stat-
ed "gain accuracy" for that conditioner, whichever represents a greater error
value (see Appendix A), and that the maximum attainable unit resolution is
±32700, fixed decimal.
4.a.6 CALCULATED CALIBRATION VIA
MNEMONIC COMMAND
"Calculated" calibration of the Model 3540 Frequency Conditioner can be per-
formed by issuing the FREQUENCY CALIBRATION (FRQ) command through
the RS-232/485 Interface Port. Similarly, the Model 3570 DC Strain Gage Con-
ditioner can be calibrated by applying the MILLIVOLT/VOLT CALIBRATION
(MVV) command. These commands are described in Section 4.d.
4.3
SETUP: INSTRUMENT CALIBRATION
4
4.a INTRODUCTION: CALIBRATION TECHNIQUES
* Except for the Model 3510 Thermocouple Conditioner, to which this technique does not
apply.
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