button to set the DECIMAL-POINT LOCATION of the displayed number. SINCE
THE PRECISION OF THE MEASUREMENTS REPORTED BY THE 3500 INSTRU-
MENT WILL ALWAYS MATCH THAT OF THE LINEARIZATION POINTS, IT IS
IMPORTANT THAT ALL "FORCE" ENTRIES BE EXPRESSED TO THE SAME
PRECISION (DECIMAL-POINT LOCATION).
7. Press ENTER. The unit will display "SET 1." You are now ready to establish
the endpoint of the first actual segment. Press ENTER once again to display
the "live" data reading.
8. Adjust the transducer load to equal a second known value (which will be "f
1
,"
the endpoint of the first linearization segment). Repeat Steps 5 through 8.
9. Continue to "force" as many linearization segments as desired (up to a total of
15).
10. If you want to modify an existing linearization table by "reforcing" a given line-
segment endpoint, you can do so by adjusting the "live" input until you reach
the line segment in question—i.e., until its number is displayed with the word
"SET." Then repeat Steps 3 through 6 and press ENTER.
11. After you have defined the last segment of your curve, press SETUP to return
to the "Setup" display.
NOTE: At any point during the "BY FORCE" procedure, you can shift to the "BY
TABLE" procedure described in Section 4.c.4(b), above, to verify the actual
numerical INPUT/OUTPUT values stored for each "forced" line-segment end-
point—and even to modify these values, if the "ideal" numbers are known. Before
moving to "TABLE" from "FORCE," however, you should first exit SETUP MODE
altogether in order to save the linearization points you have entered so far.
4.c.5 “CALCULATED” CALIBRATION
Remember that in "TWO-POINT" calibration (Sections 4.c.2 and 4.c.3.), the SCAL-
ING FACTOR ("m" coefficient) and ZERO OFFSET ("b" term) were automatically
computed as the two calibration points were established. The "CALCULATED"
calibration technique allows you to enter these two constants directly.*
4.c.5.a FOR THE MODELS 3510, 3530, 3540, AND 3560
As mentioned earlier, for the Model 3510 Thermocouple Conditioner or the
Model 3530 LVDT Conditioner, this calibration method is useful only if you want
to transfer the calibration of one instrument to another instrument that uses the
same transducer/cabling system.
For the Model 3540 Frequency Conditioner or the Model 3560 Voltage Con-
ditioner, it is generally convenient only when the instrument is used to measure
frequency or voltage itself (respectively).** In this case, you would calibrate the
4.16
4
SETUP: INSTRUMENT CALIBRATION
4.c CALIBRATING THROUGH THE FRONT PANEL
* When calibrating a conditioner in this way, keep in mind that the resulting accuracy is limited to
either the stated "initial offset" accuracy or the stated "gain accuracy" of the conditioner,
whichever represents a greater error value (see Appendix A), and that the maximum attainable
unit resolution is ±32700, fixed decimal.
** "Calculated" calibration of the Model 3540 can be accomplished through the RS-232/485
Interface by means of the FRQ command, described in the next section.
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