Rane NM 48 - Manual (Page 12)

Manual-12
(hidden or password-protected web pages) can then be created
to provide any level of system parameter access desirable—
from complete system control, to a lone system power button
or anything in-between. No longer are systems limited to the
number of security levels provided by vendor’s software, nor
are you limited to controlling a single system parameter per
screen control. For example, you can link multiple ActiveX
controls to a single screen object, thus adjusting EQ level
simultaneously with master level control and limiter thresh-
old. You can also program actions when certain events occur,
such as triggering audio playback or turning a system off at a
certain time or adjusting delay time as the temperature
changes.
You can control different parameters inside the same
device from different computers on the network as well as
controlling the same parameter from multiple computers. This
is one of the major advantages of networks – multiple control
locations will automatically be updated when changes are
made by any control location.
Microsoft FrontPage 2000 ActiveX Example
Many use Microsoft’s FrontPage 2000 to create user
interface web pages for computer-controlled systems. These
web pages may or may not be accessible over the Internet.
Once you master the ActiveX concept, using FrontPage with
ActiveX provides literally an infinite number of programming
possibilities. More information about the NM 48’s ActiveX
controls and the ActiveX controls for Rane’s RW 232 devices
is found in the sections on the next page.
NM 48 ActiveX Example
The short version of the FrontPage 2000 procedure used to
setup a web page with ActiveX controls for a Rane NM 48
device’s parameters goes as follows:
Insert a Rane NM 48 ActiveX control in a new web page.
(This software/control ships with the unit or can be found on
our RaneROM or on our website. Running this NM 48 setup
procedure registers the Rane NM 48 ActiveX control with the
computer used to create the web page. Otherwise, no special
icon or folder is created after running the setup, so save time
by not looking for the NM 48 software/control other than
from within FrontPage’s ActiveX list.) Set the inserted NM
48 control’s Properties for your application. Generally, from
FrontPage’s ActiveX Control Properties window, this
involves providing a unique Name in the Object Tag tab for
the control. Then, link this control to the specific NM 48
device by entering the NM 48 device’s IP address in the NM
48 SNMP Control Setting tab. The NM 48 control also must
be assigned an update rate which is found on the NM 48
SNMP Control Setting tab. A good default value might be “5”
which provides an update every half second. Don’t get
overzealous with this update rate since it’s a function of many
things and can negatively affect the speed at which controls
and parameter changes take effect.
Next, insert an ActiveX slider, button or what have you
from the vast list of available ActiveX controls. If you can’t
find a control that suits your fancy, further ActiveX controls
can be found on the Internet as shareware, bought from
ActiveX providers often in packages or created from scratch
for complete customization. Adjust the size, orientation and
placement of the control for optimum ergonomics being sure
to consider the user, the application and the requirement for
further controls on this same page. Keeping the number of
total controls on any one page low is very wise. See why in
the September 2000 AES preprint by Rane’s Stephen Macatee
and Devin Cook titled Controlling Audio Systems With
ActiveX Controls Over CobraNet And Other Ethernet-Based
Networks.
In the ActiveX Control Properties window for the slider
(or button…), uniquely Name the control in the Object Tag
tab. Then in the Parameters tab, set the control’s maximum
and minimum value to match the NM 48 device’s parameter
that you’ll link to this slider. Sometimes you’ll find that
you’ll need to adjust these maximum and minimum values
here (or in the Script language discussed next) to properly
display or be compatible with the parameter being adjusted.
For example, the “Mic_Trim” ActiveX control has a mini-
mum value of “0” and a maximum of “36,” but the actual
displayed range of the Trim control is -20 to +16 dB in 1 dB
steps. Thus, there are “36,” 1 dB steps. Also, often the control
link may be backwards such that the maximum value may
correspond to the “lowest” slider position. Fix this when
updating the control by subtracting the control’s maximum
setting from the desired setting within FrontPage’s VBScript
language.
To link the slider to the desired NM 48 internal device
parameter, use Microsoft’s VB Script language by associating
the slider’s Name with the specific NM 48 Control Name.
You’ll find the list of valid NM 48 ActiveX Control Names at
the end of this Manual.
To track slider or system changes and update either the
web page, the NM 48 device, or both, we’ll need to use
Microsoft’s Visual Basic Script language. This is where the
programming comes in. Yes, it does say programming.
Remember when you could do your job without the need to
program anything except the time on your wind up watch?
Some programming tasks here are things like initializing the
controls with valid information usually by reading the NM 48
device’s current settings, then updating the on-screen controls
so they match the device. You also need the Script software to
scan for any changes and make updates accordingly. It is also
wise to be sure that any requested changes to parameter
values are within the proper numerical range, thus avoiding
strange and unpredictable behavior. This is usually called
“bounds checking” by programmers. Since these web page
and network technologies allow multiple control locations, be
sure your code handles this. For example, NM 48 device
parameters can be changed from the NM 48’s front panel,
from the web page itself, from another copy of the same web
page being run elsewhere on the network, or changes can also
be made from contact closure memories. Take this into
account when writing the “update settings” code by scanning
independently for changes to the device’s settings and
changes to the web page controls. Then update things so the
device settings and the web page controls always match.