Rane NM 48 - Manual (Page 11)

Manual-11
For the LCR and stereo FM broadcast feeds, you could use
hard-wired cable runs which may be less expensive. Or, use a
single CAT 5 cable, three CobraNet devices and a couple of
dedicated repeater hubs and utilize a single Multicast Bundle
(1 through 255) to transmit all 5 audio channels to both the
remote LCR and FM locations from the front of the house.
Now let’s make things fun and assume, since this church
pays no taxes, that their infinite budget (so common these
days) requires an audio system in the church’s on-site hotel
and gymnasium. Oh, how fun.
The church’s hotel, gymnasium and attached convention
center requires a dozen stereo channels of background music
as well as 4 paging audio feeds. Additionally, the LCR and
stereo feeds from the church are fed into the gymnasium and
convention center for more overflow on Christmas, Easter and
when Father Guido Sarducci is in town.
Including the 12 stereo background feeds on the network,
allows the church complex access to these background music
sources for intermissions and open houses.
I think you can see where this is going. By using a
combination of multicast and unicast networking, you can
easily use CobraNet technology to efficiently distribute many
audio channels to and from many locations and save consider-
able money on cable, conduit, labor and the re-configuration
time needed to accommodate the wide variety of audio
distribution needs in large and small facilities.
CobraNet network designs must not exceed 32 Multicast
Bundles per VLAN. A VLAN (virtual LAN) is an advanced,
“Networking 401” term associated with managed switches
used on only the most advanced systems. Managed switches
allow point-to-point virtual LANs to be defined by the
network designer.
Software and Applications
ActiveX and Software issues
Microsoft ActiveX controls (defined in the next section)
are of concern to the pro audio community. This technology
allows designers of computer-controlled sound systems to
create common front-end software control panels that operate
different manufacturers’ units, without having to know
anything about their internal code or algorithms. This is
powerful. When more manufacturers jump on the ActiveX
bandwagon, systems designers will no longer be limited by
the products offered by a single, platform-specific (i.e., closed
architecture) manufacturer.
What is ActiveX anyway?
ActiveX is a Microsoft-developed software technology
released in 1996. ActiveX, formerly called OLE (Object
Linking and Embedding), is loosely based on the Component
Object Model (COM), but provides substantially different
services to developers. At this point, you might think:
WHAT!?^* But keep reading! An ActiveX control is a unit of
executable code (such as an .EXE file) that follows the
ActiveX specification for providing software objects. This
technology allows programmers to assemble reusable soft-
ware controls into applications and services. However,
software development using ActiveX technology should not
be confused with Object-Oriented Programming (OOP). OOP
is concerned with creating objects, while ActiveX is con-
cerned with making objects work together. Simply stated,
ActiveX is a technology that lets a program (the ActiveX
control) interact with other programs over a network (e.g., the
Internet or Ethernet), regardless of the language in which they
were written. ActiveX controls can do similar things as Java,
but they are quite different. Java is a programming language,
while ActiveX controls can be written in any language (e.g.,
Visual Basic, C, C++, even Java). Also, ActiveX runs in a
variety of applications, while Java and Javascript usually run
only in Web browsers. ActiveX controls can be used in web
pages and within visual programming languages such as
Borland’s Delphi, Sybase’s PowerBuilder, Microsoft’s Visual
Basic and even in tools such as Adobe’s GoLive,
Macromedia’s DreamWeaver and National Instrument’s
LabVIEW.
In English, for our pro audio applications, ActiveX control
objects are the sliders, buttons, indicators and other graphical
screen entities. The objects have properties such as slider
position and slider range and on or off for buttons and
indicators, etc. Once the screen objects are chosen and placed,
further ActiveX controls can then be used to link the object’s
properties to other ActiveX controls. Thus, allowing linking
an ActiveX slider to the ActiveX control for a device’s level
control. Then moving the level control graphic slider subse-
quently varies the audio level and vice versa.
Each ActiveX control is made up of Properties and
Events. ActiveX control Properties are values associated with
the control, which might include such things as level settings,
mute condition and meter readings. ActiveX control Events
tell the computer something significant has happened, such as
a switch closure, button press or clip detection.
ActiveX allows the manufacturer to create an object (a
piece of software code) which fully describes a device, while
hiding the implementation details such as protocol from the
programmer. By hiding the communication details, there is no
longer a need for different manufacturers’ to agree on
protocol. This lack of a protocol standard means that coopera-
tion between manufacturers is not required. It allows each
manufacturer to choose the best protocol for their devices.
For example, no longer would you need to know that the
17th byte of a 32-byte status message meant that the unit’s
second output channel was muted. With an ActiveX control,
you might simply refer to the device’s output 2 mute status as
“Device1.Out2Mute”. See the RaneNote “Emerging Stan-
dards for Networked Audio System Control” and “Controlling
Audio Systems with ActiveX Controls over CobraNet and
other Ethernet-based Networks,” both downloadable from the
Rane website Library.
Implementing ActiveX controls
An example might help clear this up. A few assumptions
are that a computer is used to control an audio system over an
Ethernet network and that something on the computer’s
screen controls some function of the system. The basic idea is
to place controls on the computer screen and link them, using
ActiveX, to a parameter in the system. What’s important here
is that only the controls required by the computer’s end user
need be displayed. Additionally, more detailed interfaces