Parameter Notes¶

Faders

Faders can be controlled to the limits of their minimum and maximum values shown in the Design View screens in Composer. A controller position of zero (0) will cause the minimum fader position to be realized. A controller position of 65535 will cause the maximum fader position to be realized. Increasing positions will move the fader linearly in dB.

Most volume faders have a range of -72dB to +12dB. In these cases, the following formula can be used to convert from controller position to dB:

Volume dB = -72 + 84*(CONTROLLER POSITION/65535)

If CONTROLLER POSITION = 0, Volume dB = OFF

For these faders, a value of 780 is approximately equal to a 1dB change in gain.

Note that some faders have a different range than -72 to +12dB. In this case, the formula will depend upon the actual fader range. The more general formula is shown below:

Volume dB = MINIMUM VALUE + (MAXIMUM VALUE - MINIMUM VALUE)*(CONTROLLER POSITION/65535)

WhereMINIMUM VALUEis the fader's lower limit in dB andMAXIMUM VALUEis the fader's upper limit in dB.

Faders with User Min and User Max Limits

There are some applications where it is desired to limit the range of adjustments for an end user, perhaps to allow a more useable range of adjustment than the full range of the fader or to prevent the system from getting too loud. To limit the gain range of a fader to a user minimum and user maximum range, the following formulae may be used.

In the following discussion, it is assumed that the range of the variables (in dB) are as follows:

MAXIMUM VALUE > User Maximum > User Volume > User Minimum > MINIMUM VALUE

The controller position is calculated the same as described previously:

To determine the controller position based on a desired User Volume in dB, then the controller value is calculated as follows:

Controller Position = (User Volume in dB - MINIMUM VALUE) * 65535 / (MAXIMUM VALUE - MINIMUM VALUE )

The percentage value of the fader control relative to the User Min and User Max values is computed as:

Volume Percent = (User Volume in dB - User Min) / (User Max - User Min)

The controller position required to set the fader to a percentage of the user min and user max may be computed as follows:

Controller Position = (Volume Percent * (User Max - User Min) + (User Min - MINIMUM VALUE)) * 65535 / (MAXIMUM VALUE - MINIMUM VALUE)

For example, if the Maximum and Minimum Values are +12 and -72, respectively, and the desired User Max and User Min are +6 and -30 respectively, then the controller value for setting the fader to -8dB is:

Controller Position = ((-8) - (-72))* 65535 / ((+12) - (-72)) = 49931

The controller position corresponding to 35% volume with the same User Max and User Min range would be:

Controller Position = (35% * ((+6) - (-30)) + ((-30) - (-72))) * 65535 / ((+12) - (-72)) = 42598

Calculating the Volume in dB from the Volume Percentage would be done as follows:

Volume in dB = (Volume Percent * (User Max - User Min)) + User Min

In this example, the volume in dB corresponding to 50% of the volume would be calculated as:

Volume in dB = 50% * ((+6) - (-30)) + -30 = -12 dB

Buttons

Buttons such as a mute or bypass can be controlled similarly with controller positions by sending the minimum value (0) to turn the switch off (button not pushed) and sending the maximum value (65535) to turn the switch on (button pushed).

Input and Output Selectors

A value of zero (0) will select the first input or output and a value of (65535) will select the last input or output. Other values are selected by sending evenly spaced (linear) values as shown by the formula below:

Controller Value = (INPUT NUMBER - 1)*65535/(NUMBER OF INPUTS - 1)

Note: for an output selector, replace "INPUT" with "OUTPUT" above.

Meters

Meters can be read via RS-232 or Ethernet. The read back value will be linear in dB with 65535 representing +24 dBu (0 dBFS) and 0 representing -48 dBu (-72 dBFS) (or less). The formula below can be used to calculate a dB reading from a controller value:

Level dBu = 72*(CONTROLLER VALUE/65535) - 48

If CONTROLLER VALUE = 0, Level dBu <= -48 dBU

Input and output meters in some other modules such as Compressors and AGCs can also be read. In this case, the read back value will be linear in dB with 65535 representing the maximum value shown on the meter and 0 representing the minimum value shown on the meter (or less). The formula below can be used to calculate a dB reading from a controller value:

Level dB = (MAXIMUM VALUE - MINIMUM VALUE) *(CONTROLLER VALUE/65535) + MINIMUM VALUE

If CONTROLLER VALUE = 0, Level dB <= MINIMUM VALUE

Where MINIMUM VALUE is the meter's lower limit in dB and MAXIMUM VALUE is the meter's upper limit in dB.

Control meters in dedicated control meter modules can also be read. In this case, the read back value will be linear with 65535 representing 100% and 0 representing 0%. The formula below can be used to calculate a percentage reading from a controller value:

Level % = 100*(CONTROLLER VALUE/65535)

Note: Meters are a "read-only"� parameter. Attempting to change the meter value will have no effect.

LEDs

LEDs in various modules can be read via the control protocol. The read back value will be either 65535 if the LED is on or 0 if the LED is off.

Note: LEDs are a "read-only" parameter. Attempting to change the LED value will have no effect.

Diagnostic Controls

Connected LED

The read back values are:

0 = Disconnected

65535 = Connected

Network Diagnostics Panel

DHCP Enabled LED - Only DHCP Enable can be read unless using SymVue. The read back values are:

0 = DHCP Disabled

65535 = DHCP Enabled

Power Supply Diagnostics Panel

All voltages are in .001V increments offset by 32768. The read back values of 0-65535 translate to -32.768V-32.767V.

Status LED - The read back values are:

0 = OK

65535 = Failed

Thermal Diagnostics Panel

Peak temperature date and time can only be read in SymVue. All temperatures are in .01 degree C increments offset by 32768. The read back values of 0-65535 translate to -327.68V-327.67V.The Fan speed is 0-65535 Hz.

Status LED – Send -65535 to clear, The read back values are:

0 = OK

65535 = Failed

Control Diagnostics Panel

All read back values:

0 = Inactive/Off

65535 = Active/On

Other Parameters

Many other parameters such as compression ratios, delay times, EQ settings and pans can also be controlled externally. In fact, almost any DSP parameter in Composer can be controlled. For other parameter types, as in the above examples, sending a value of zero (0) will set the parameter to its minimum value and sending a value of (65535) will set it to its maximum value. Ratios, frequencies, width/Q, and attack/release/hold times all use a logarithmic scale. Pans and delay times use a linear scale. Quantities expressed in dB such as gains, volumes, thresholds and depths are linear in dB. When in doubt, experiment by changing a value from the control application and reading it back via RS-232 or Ethernet.

Parameters That Cannot Be Controlled Externally

The following Composer features cannot be controlled externally. In some cases, work arounds are suggested.