e. Now apply an accurately known value of input loading to the source trans-
ducer—a value (positive or negative) from 80% to 100% of the nominal full-
scale rating.
f. Enter a command of
FRC x = z [CR]
where “z” is the numerical value of the known input applied in Step e, in
desired engineering units and with appropriate polarity. This command
“forces” the data reading of Channel No. x to equal the value “z.” It there-
by sets the “EMM” value for Channel No. x—that is, the SCALING FACTOR
to be applied to all subsequent channel readings. Check the “live” display
of Channel No. x to make sure that it reads the number “z.”
The
FRC command also set the desired precision of Channel No. x. Sup-
pose, for example, that you’re measuring “pounds,” and enter a “z” of
“300.” All subsequent readings of Channel No. x will be rounded to the
nearest pound. If, however, the entry is “300.0,” then all readings will be
rounded to the nearest tenth of a pound.
g. Remove all load from the source transducer. The “live” display of Channel
No. x should return to zero. Check the accuracy of the calibration by
applying various amounts of known loading to the transducer and noting
the corresponding measurement readings on the channel’s “live” display.
(You may have to repeat Steps c through g to achieve final calibration.)
h. Do not disconnect the transducer. It will be used in some of the following
procedures.
NOTE: Section 2.G of the
System 10 Guidebook shows you how to set a data
channel’s SCALING FACTOR and ZERO OFFSET directly, using the
SCALING
FACTOR (EMM)
and OFFSET (BEE) commands, respectively. Section 2.G
also tells you how to set a channel’s digital filter by means of the
FILTER (FIL)
command, and also, if desired, a “run-time” tare offset value, by means of the
TARE (TAR) command.
11
SETUP OF CROSS-
CHANNEL CALCULATIONS
In this section, you will apply the CALCULATE (CLC) command to define a
system “CALCULATE” channel.
A CALCULATE channel is one form of System 10 “pseudochannel.” Its report-
ed data does not represent a directly measured value, but rather a mathemat-
ical function of one or more other data channels (“real” or “pseudo”). In
addition to standard algebraic operations, CALCULATE functions include
square root, absolute value, maximum (most positive value), and minimum
(least positive value). They permit real-time computation of such process vari-
ables as Efficiency, Horsepower, Specific Fuel Consumption, Power Factor,
Lift-Drag Ratio, Spring Modulus, and many others.
The thirteen forms of the
CLC “WRITE” command are listed in Section 2.J.1 of
the
System 10 Guidebook. Here, we will use only the first of these functions
(multiplication of a single channel by a constant) to demonstrate the use of
the
CLC command. You will multiply the “live” data value for Channel No. x—
the channel you calibrated in the previous section—by a given numerical con-
stant. Examples of more complex cross-channel calculations are given in
Section 2.J of the
System 10 Guidebook.
A - 16
SETUP OF CROSS-CHANNEL CALCULATIONS
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