AMX Signature Series NetLinx Integrated Controller NI-3101-SIG - Manual (Page 93)

NetLinx Security within the Web Server
83 NI-3101-SIG Signature Series NetLinx Integrated Controller
What is Dynamic Device Discovery?
The Dynamic Device Detector (DDD) monitors the system for newly connected devices. New devices can be
detected via either an external discovery protocol manager (built into firmware
build 320 or higher
), 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".
FIG. 66 System Settings - AMX License Agreement page
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 interface (page 89).
SDK Class: • Each application device in the DDD world is associated with a particular 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.
Accept button