cdev
Class DeviceContext

java.lang.Object
  |
  +--cdev.DeviceContext

public class DeviceContext

extends java.lang.Object

The DeviceContext class provides the encapsulation into an object of the parameters that condition the execution of the I/O methods (analogous to a graphics context for screen I/O). Devices can (and do by default) share the same DeviceContext. A default DeviceContext is provided for an "application", based on the thread group name. The DeviceContext is implemented as a cdev.Data, a collection of name-value pairs, and a context number which changes whenever any of the entries change. This class includes a static device context which has a number of flags (entries with value=1) preset to force a read of a property to also retrieve a large number of characteristics (limits, units, etc.). Convenience routines have been created to manipulate a number of commonly used flags:

Valid tags	Data type	Usage
cycleType	String or int	Cycle type condition.
timingEvent	String	Timing event.
timeOut	double	A time out value for I/O methods execution, in seconds.
count	int	User-specified number of values to return.
referenceKey	String	Reference value set identifier
onChange	any	If present, the "on-change" mode is active for monitors

Constructors use the following system properties: (this list should later be made configurable)

• cdev.context.cycleType
• cdev.context.onChange

Constructor Summary

DeviceContext()

DeviceContext(Data d)

Method Summary

Data	getData()
static DeviceContext	getDefault()
static DeviceContext	getDefault(java.lang.String name)
int	getSequenceNumber()
void	setCycleType(java.lang.String cycleType) Stores a cycle type selection into this DeviceContext.
void	setData(Data d)
static void	setDefault(DeviceContext ctx)
static void	setDefault(java.lang.String name, DeviceContext ctx)
void	setReferenceKey(java.lang.String referenceKey) Stores a referenceKey (archive name) selection into this DeviceContext.
void	setTimeOut(double timeOut) Stores a timeOut value into this DeviceContext.
void	setTimingEvent(java.lang.String timingEvent) Stores a timing event selection into this DeviceContext.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DeviceContext

public DeviceContext()

DeviceContext

public DeviceContext(Data d)

Method Detail

setDefault

public static void setDefault(DeviceContext ctx)

setDefault

public static void setDefault(java.lang.String name,
                              DeviceContext ctx)

getDefault

public static DeviceContext getDefault()

getDefault

public static DeviceContext getDefault(java.lang.String name)

setData

public void setData(Data d)

getData

public Data getData()

getSequenceNumber

public int getSequenceNumber()

setCycleType

public void setCycleType(java.lang.String cycleType)

Stores a cycle type selection into this DeviceContext. Checks first if new selection.

setTimingEvent

public void setTimingEvent(java.lang.String timingEvent)

Stores a timing event selection into this DeviceContext. Checks first if new selection.

setReferenceKey

public void setReferenceKey(java.lang.String referenceKey)

Stores a referenceKey (archive name) selection into this DeviceContext. Checks first if new selection.

setTimeOut

public void setTimeOut(double timeOut)

Stores a timeOut value into this DeviceContext. Checks first if new value.