oCycleTimeL Object

Description
Operation
Properties

Examples
Related
Version History & Bug list

Measures the cycle time of an low-frequency input on any I/O line.

The oCycleTimeL Object is capable of measuring the approximate frequency of a square wave input with a frequency of up to 283Hz. (see note)

Typical applications are bicycle speedometers or any other application that provides a low-frequency square wave. The Hamamatsu UVTron Flame detector also outputs a signal that can be read by this object. (see related items)

The following table lists the size and availability of the oCycleTimeL Object.

	Object	Size	Description	A1	A2	B1	B2	C1
	oCycleTimeL	6 Bytes	Measures the cycle time of an low-frequency input on any I/O line.			x	x	x

Operation:

When the Operate property is 1, the oCycleTimeL Object monitors the I/O line specified by the IOLine property for a high-going transition. When the input transitions to a high state, a counter is started at 255. The counter will then decrement at a rate of 283Hz. When the next high-going transition occurs, the count is copied to the duration property and the process starts again.

If no high-going pulses are detected, or the high-going pulses are more than ~0.9 seconds apart, the counter will eventually count down to 0 at which time the counter stops. Thus, a cycle time of longer than approximately 0.9 seconds will read 0.

The Duration property is calculated from the following formula: Duration = (256 - (283 / Frequency))
Inversely, the Frequency can be calculated from the Duration: Frequency = (283 / (256-Duration))

Note that the Duration is not a linear property. As the frequency goes up, the Duration increases at a quicker rate. Thusly, while the the oCycleTimeL Object is capable of measuring a frequency of up to 283hz, it is best at measuring frequencies below 5Hz. (See Duration property table)

If the input has a frequency of more than 283hz then the high going pulses will happen before the counter gets to decrement one time. Thus, a cycle time shorter than approximately 0.0035 seconds will read 255.

Properties:

The following table lists the properties of the oCycleTimeL Object:

Property
Description

Duration

A value that indicates the current duration of one cycle.

Object Class: oByte Value Range: 0 - 255

Data Type: Numeric Default Value: 0

Determines the duration using the following formula: Duration = [256 - (283 / Frequency)

Duration Description

0 The cycle duration is greater than ~0.9 seconds.

1 The cycle duration is ~0.90 seconds. (1.105hz)

2 The cycle duration is ~0.89 seconds. (1.110hz)

3-252 The cycle duration is between ~0.89 and ~0.014 seconds.

253 The cycle duration is ~0.014 seconds. (94.33Hz)

254 The cycle duration is ~0.007 seconds. (141Hz)

255 The cycle duration is ~0.0035 seconds (283Hz) or less.

IOLine

A value that specifies which I/O Line to use for the frequency input.

Object Class: oIOLine Value Range: 0 - 31

Data Type: Numeric Default Value: 0

Some I/O Lines have special purposes. Be sure to see oIOLine help file for details.

Operate

A value that selects whether or not the cycle duration is measured.

Object Class: oOperate Value Range: 0 - 1

Data Type: Numeric Default Value: 0

Operate Constant Description

0 cvOff The cycle duration is not measured.

1 cvOn The cycle duration is measured.

Address

Returns a pointer to the address of the oCounter Object instance.

Object Class: oAddress Value Range: 0 - 127

Data Type: Pointer (Read Only) Default Value: Address of Object

Examples:

In the following example, the oCycleTimeL Object is used.

Visual Basic Syntax

C and Java Syntax

'This program reads the cycle 
'time of an input on I/O line
'1 and outputs the duration 
'on I/O lines 8 - 15.

Dim A As New oCycleTimeL 
Dim B As New oDIO8
Dim C As New oDIO1

Sub Main()
  A.IOLine = 1
  A.Operate = cvTrue
  B.IOGroup = 1
  B.Direction = cvOutput
  C.IOLine = 31
  C.Direction = cvOutput
  Do
    B.State = A.Duration
    C.State = A.Duration.NonZero
  Loop
End Sub

//This program reads the cycle 
//time of an input on I/O line
//1 and outputs the duration 
//on I/O lines 8 - 15.

oCycleTimeL A = New oCycleTimeL ;
oDIO8 B = New oDIO8;
oDIO1 C = New oDIO1;

Void Main(Void){
  A.IOLine = 1;
  A.Operate = cvTrue;
  B.IOGroup = 1;
  B.Direction = cvOutput;
  C.IOLine = 31;
  C.Direction = cvOutput;
  Do{
    B.State = A.Duration;
    C.State = A.Duration.NonZero;
  } While (1)
}

Basic Syntax

'This program reads the cycle 
'time of an input on I/O line
'1 and outputs the duration 
'on I/O lines 8 - 15.

A As oCycleTimeL 
B As oDIO8(1,cvOutput)
C As oDIO1(31,cvOutput)

A.IOLine = 1
A.Operate = cvTrue

Do
  B.State = A.Duration
  C.State = A.Duration.NonZero
Loop