Levels; Introduction To Levels; Creating Levels - AMX AXCESS CONTROL SYSTEM PROGRAM Instruction Manual

Levels

Introduction to Levels

Devices such as volume control cards, voltage generator cards, and pan/tilt control cards use levels
to interface with the outside world. Levels are values related to an analog input or output on an
Axcess device. Several Axcess panels have bargraph displays capable of displaying a level.
An input/output (I/O) channel in Axcess is usually digital in nature; that is, it is always either in an
ON or OFF state. However, several Axcess devices, such as the volume control card and the pan/tilt
control card, have analog input and/or output capabilities. An analog input or output may have
many different states. Devices using analog I/O internally store the values relating to the state of
each of these analog inputs and outputs; these values are called levels. On a volume card, levels
relate to the volume levels of the card. Levels can be used to tell a pan/tilt control card where to
position a camera, or tell a voltage generator card the amount of voltage to generate.
For conceptual purposes, imagine that a volume control card has two volume knobs: one for the left
speaker and one for the right, as shown in FIG. 11. Each knob has a value range from Ø to 255.
These knobs represent the two levels present in the volume control card. When a level is discussed
in the text, it is usually referring to the value of one of these imaginary knobs.
FIG. 11 The imaginary knobs. The knob is the level, which can have a range of values.

Creating Levels

Most devices have level ranges of Ø to 255.
A few devices have level ranges larger than Ø to 255, but the programming principles
and examples in this section still apply.
Level values can be stored in a variable for later use. To read a level from an Axcess device that
supports levels, use the keyword CREATE_LEVEL. Here is the syntax:
CREATE_LEVEL device, level number, variable
CREATE_LEVEL requires three parameters:
!
!
!
This keyword creates an association between the specified level of the device and the specified
variable. During the execution of your program, Axcess will continually update the variable to
Axcess Programming Language
The device from which to read the level.
Which level of the device to read (some devices have many different levels).
The variable in which to store the level.
Levels
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