Red-lion PAX2D User Manual download pdf (Page 12)

SCALING CALCULATION

Each counter has the ability to scale an input signal to a desired display value.

This is accomplished by the counter mode (Cnt x), decimal point (dEC Pt), scale

factor (SC FAC), and scale multiplier (SCALEr). The scale factor is calculated using:

SF (SC FAC) = DDD

(Number of pulses per ‘single’ unit X CMF X SM)

Where:

Number of pulses per ‘single’ unit: pulses per unit generated by the

process (i.e. # of pulses per foot)

CMF: Counter Mode(Cnt x) times factor of the mode 1,2 or 4.

SM: Scale Multiplier (SCALEr) selection of 10, 1, 0.1 or 0.01.

DDD: Desired Display Decimal (1 =1, 1.0 = 10, 1.00 = 100, etc.)

Example:

1. Indicate feet to the hundredths (0.00) with 100 pulses per foot:

Scale Factor would be 100 / (100 x 1 x 1) = 1

(In this case, the scale multiplier and counter mode factor are 1)

2. Indicate feet with 120 pulses per foot: Scale Factor would be 1 / (120 x 1 x 1)

= 0.0083333. (In this case, the scale multiplier of 0.01 could be used: 1 / (120

x 1 x 0.01) = 0.83333 or show to hundredths (0.00): 100 / (120 x 1 x 1) =

0.8333.)

General Rules on Scaling

1. It is recommended that, the scale factor be as close as possible to, but not

exceeding 1.00000. This can be accomplished by increasing or decreasing the

counter decimal point position, using the scale multiplier, or selecting a

different count mode.

2. To double the number of pulses per unit, use counter modes direction X2 or

quad X2. To increase it by four times, use counter mode quad X4. Using these

modes will decrease the allowable maximum input frequency.

3. A scale factor greater than 1.00000 will cause Counter display rounding. In

this case, digit jumps could be caused by the internal count register rounding

the display. The precision of a counter application cannot be improved by

using a scale factor greater than 1. 00000.

4. The number of pulses per single unit must be greater than or equal to the DDD

value in order for the scale factor to be less than or equal to one.

5. Lowering the scale factor can be accomplished by lowering the counter

decimal position. (Example: 100 (Hundredths)/10 pulses = 10.000 lowering

to 10 (Tenths)/10 = 1.000.)

Pro

INPUt

RAtE

RAtE x

Rtx

Rate x

Enable

dEC Pt

Rtx

Rate x

Decimal

Position

StYLE

kEY

Rtx

Rate x Input

Scaling Style

SC PtS

Rtx

Rate x

Scaling

Points

Rx dSP

Rate x

Display Value

Scaling Point

Rx INP

0.0

Rate x

Input Value

Scaling Point

ROUNd

Rtx

Rate x

Display

Rounding

LO-CUt

Rtx

Rate x Low

Cut-Out

RAtE C

NONE

RtC

Rate C

Calculation

SCALEr

RtC

Rate C

Display

Multiplier

HI-Udt

2.0

SEC

Rate High

Update Time

LO-Udt

1.0

SEC

Rate Low

Update Time

dEC Pt

RtC

Rate C

Decimal

Position

SELECt

RAtE x

x = A or b

# = Scaling Point Number (1-10)

Hi ASN

RAtE A

MAX Value

Assignment

Hi CAP

1.0

SEC

MAX Capture

Delay Time

Lo CAP

1.0

SEC

MIN Capture

Delay Time

Lo ASN

RAtE A

MIN Value

Assignment

SELECt

Hi-Lo

SELECt

RAtE C

SELECt

UPdAtE

Pro

RATE INPUT PARAMETERS (RAtE)

This section details programming for the Rate indicators (A, B and C) and the Maximum and Minimum Rate Capture displays. For maximum input

frequency, the Rate indicators should be disabled when they are not in use. When Rate Enable (Rate A and B) or Rate Calculation (Rate C) is set to NO or NONE,

the remaining related parameters are not accessible. In the display depictions shown in this section, “x” represents A or B for the rate indicator being

programmed.

RATE SELECTION

RAtE A RAtE C Hi-Lo

RAtE b UPdAtE

Select the Rate parameters to be programmed.

RATE ENABLE

NO YES

Select YES to measure the rate (speed) of pulses on the corresponding Input.

Rate measurement is independent of the corresponding Counter count modes.

RATE DECIMAL POSITION

0 0.00 0.0000

0.0 0.000

This selects the decimal point position for the selected Rate indicator.

RATE SCALING POINTS

2 to 10

This parameter sets the number of scaling points for the Rate Scaling

function. The number of scaling points used depends on the linearity of the

process and the display accuracy required.

About Scaling Points

Each scaling point is specified by two programmable parameters: A desired

Rate Display Value (Rx dSP) and a corresponding Rate Input Value (Rx INP).

Scaling points are entered sequentially in ascending order of Rate Input value.

Each scaling point defines the upper endpoint of a linear segment, with the lower

endpoint being the previous scaling point.

Linear Application – 2 Scaling Points

Linear processes use two scaling points to provide a linear Rate display from

0 up to the maximum input frequency. For typical zero based frequency

measurements, the lower point is set to display 0 for 0 Hz input (factory setting)

and the upper point set to display the desired value for a given input frequency.

For non-zero based applications, the lower point is set to the desired display for

0 Hz input.

SELECt

RAtE A

RAtE X

Rtx

dEC Pt

Rtx

SC PtS

Rtx

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 35 36

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Red-lion PAX2D User Manual Page 12

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