Adding Devices to the System
56
VisualArchitect v1.1
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Dynamic Device Discovery Protocol (DDDP)
NetLinx Masters equipped with firmware build 320 or higher support Dynamic Device Discovery, via
the Dynamic Device Detector (DDD).
The Dynamic Device Detector (DDD) monitors the system for newly connected devices. New devices
can be detected via either an external discovery protocol manager, Multicast reception of a Dynamic
Device Beacon, or via the receipt of a beacon response on an application specified list of serial devices.
This DDD process begins by detecting new devices within a NetLinx/Duet system, binding those devices
to application instances, and then starting a Duet module to control those new devices.
Dynamic Device Discovery was created to take advantage of Java's Dynamic Class Loading and the
Duet Standard NetLinx API (SNAPI). Java loads classes as they are needed. Therefore it is feasible to
load a Duet control/protocol module on the fly as each new device is discovered. SNAPI provides a fixed
interface for communicating with a certain type of device. The "glue code" refers to the developer
defined NetLinx program that runs on a Master and controls a system.
Take for example a VCR. The majority of control features are common to all VCRs (play, stop, pause,
etc.). SNAPI provides the "glue code" developer the ability to write common code that will control any
type of VCR having an associated Duet module. The underlying Duet module could be swapped in and
out based on the actual physical device with no changes needed to the higher level "glue code".
Dynamic Device Discovery Concepts
Feature Description
• Application Device:
A Duet Device (41000-42000) that is used as a control interface to a
physical device. This is also referred to as the Duet virtual device. All
control requests are made to the application device rather than to the
physical device.
• Binding:
In concrete programming, the application device is forever associated
with the NetLinx physical device. In DDD, this association is dynamic.
The act of associating an application device with a physical device is
called "binding".
• Device Discovery:
In DDD, physical devices are detected in the system at run-time. There
are two different methods of detection: via Dynamic Device Discovery
Protocol (DDDP) or via user definition within the Master's Web inter-
face.
• SDK Class:
Each application device in the DDD world is associated with a particu-
lar device type as defined by SNAPI. When using a VCR or a Receiver
as an example, each of these device types would correspond with a
Java Interface within the Duet Device Software Development Kit
(SDK). When writing programs for DDD, the developer specifies the
device type of a particular application device by using one of these
SDK Class names.
• Polling:
Dynamic physical devices can be detected by DDDP through both
Serial and IP interfaces. But whereas IP connections are then able to
utilize the network's higher layers of multicast to broadcast their exist-
ence, Serial devices speak a fixed protocol that is incompatible with
DDDP. Serial devices are passive and will only broadcast their exist-
ence if polled to do so. The program developer must specify which
NetLinx interfaces/ports (i.e. serial ports) should be polled for devices.
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Страница 26: ...VisualArchitect v1 1 Overview 14 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 36: ...Creating a New VA Project 24 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 102: ...Setting Device Properties 90 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 106: ...Defining Control Strings 94 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 158: ...Finishing the Project 146 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 214: ...Appendix D AMX Icon 2 Character Map 202 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
Страница 240: ...Appendix F The InConcert Resource Center 228 VisualArchitect v1 1 CONFIDENTIAL AND PROPRIETARY COPYRIGHT AMX LLC 2006 ...
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