DayTronic System 10 User Manual Book Download

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ONFIGURATION AND

ALIBRATION

1.G

NALOG

NPUT

HANNELS

1.G.2

ETHODS OF

ALIBRATION

System 10 channels requiring CALIBRATION are those that contain physical mea-
surement data from the “real world.” These include

•

“REAL” (ANALOG INPUT) CHANNELS

“sourced” by Daytronic SIGNAL CON-

DITIONER CARDS*

•

Peak Capture / Track-Hold

channels based on “real” channels (for the cali-

bration of channels derived from the

Model 10A79-4 Analog Peak Capture

Card

, see Section 3.A.4 of this Guidebook)

All other channel types—”PSEUDOCHANNELS,” “CONVERSION CHANNELS,”
etc.—do not require calibration.**

In most cases, several alternative calibration methods will be available for a data
channel originating from a given Conditioner Card. Which method you choose
will depend on

•

the type of source transducer for the channel

•

the precise characteristics of the transducer/cable/conditioner combination

•

the extent of your knowledge of these characteristics

•

the possibility and/or convenience of producing actual or simulated transduc-
er inputs of accurately known value

In general terms, you will calibrate a signal-conditioner channel by commanding
the System 10 Central Processor to compute and store two constant values: a

SCALING FACTOR (“m”)

—also called “multiplier” or “gain” factor—and a

ZERO

OFFSET (“b”)

. Automatically and continuously applied to all subsequent read-

ings of the given channel, these two CALIBRATION CONSTANTS define the linear
proportionality expressed by the equation

y = mx + b

, where “y” is the measure-

ment value reported for the channel and “x” is the ratio of the actual voltage of the
analog input signal to the positive full-scale voltage of the channel’s chosen input
“TYPE.” As such, “x” is a unitless number operated upon by the “slope” coeffi-
cient “m” and the offset term “b” to yield a true analog measurement. Both “m”
(

EMM

) and “b” (

BEE

) are to be expressed in the engineering units of the chosen

input “TYPE.”

PLEASE NOTE:

As explained in Section 1.G.3, “ABSOLUTE” calibration of a fre-

quency-, current-, or voltage-measuring channel involves the direct setting of the
channel’s “m” and “b” constants by application of the

SCALING FACTOR (EMM)

and

ZERO OFFSET (BEE)

commands, respectively. For all other calibration

techniques, it is normally the case that both “m” and “b” are automatically calcu-
lated and stored by the Central Processor during the run-time calibration proce-
dure, and are NOT ENTERED DIRECTLY BY THE USER via the

EMM

and

BEE

commands.

In fact, certain

EMM

and

BEE

values (other than the normal defaults) are auto-

matically loaded for certain channel types as soon as those types are defined.
Thus, for a thermocouple-based “real” channel or other channel capable of
“ABSOLUTE (CPU)” calibration, specific “m” and “b” values are loaded as soon as
the channel is “typed.” These values should normally NOT BE CHANGED.

1-34

1.G.2 M

ETHODS OF

ALIBRATION

* With the exception of channels based on the

Model 10A35 Encoder Conditioner Card

** Except for LINEARIZATION (“LIN”) channels, whose calibration is strictly based on prestored

“look-up” tables (see Section 2.L).