User Guide

Appendix B: AMX Lighting Curves
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AMX Lighting PROlink/AXlink Programming
off-state at level 0 to an on-state at level 100. Dimmer output is measured in volts. A graphical
representation of a dimming curve is usually the percentage of dimming in relation to the output
voltage (RMS) of the dimmer connected to a standard load.
AMX Lighting curve changes are implemented by a Send_String command to the AMX Lighting
device. The command structure is: "<dimmer>/<curve><enter>" ; SEND_STRING LTS, "'1/6',13".
This example would set dimmer channel #1 to curve 6. The available curves that can be sent to the
AMX Lighting controller are: 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, N, O, and F.
The AMX Lighting dimming system employs a low-end cutoff that allows the dimmer to turn on to
a specified level or to dim down to a specific level. The level at which the dimmer turns on is called
the Low End Setting. This is also used to turn a light off at the low end point when dimming down
from a bright level. A low end setting of 25 applied to the standard dimming curve would prevent
the fixture from being dimmed below Level 25. From an off condition the same fixture would dim
up to Level 25 and hold that level until the dimming curve directed the level higher.
The Low End Setting uses a Send_String command to the AMX Lighting controller. The command
structure is: <dimmer>LE<level><enter>; SEND_STRING LTS, "'1LE20',13". This example
would set the Low End Setting for dimmer channel #1 to 20%. This would prevent dimmer #1 from
dimming below dimmer level 20.
If a fixture flickers just before it goes out then the Low-End Setting can be used to avoid the
unusable dimming range. Set the Low-End Setting to just above the level where flickering problem
starts. This will prevent the dimmer from allowing the flicker to be seen.
Dimmer manufacturers follow or adopt a level to output ratio called the Square Law curve. It is an
exponential relationship between percentage of light perceived and the percentage of light
measured. The Square Law Curve is a presumed relationship between perceived illuminance and
measured illuminance. The AMX Lighting controller's Curve 1 is a basic Square Law Curve. From
this basic curve, AMX has developed a set of curves other than standard to accommodate the many
different properties of the various loads connected to a AMX dimmer. Multiple curves provide a
user with multiple ways to control lighting. This will provide lighting designers with a more
powerful lighting tool.
To demonstrate how a AMX dimmer actually performed under real conditions, we have adopted a
set of uniform tests to display the output characteristics of a dimmer.
The AMX test fixture for incandescent tests was set up using a constant Voltage feed of 120 VAC to
the dimmer. The output of the dimmer was connected to (6) 100W GE lamps with a total load of 5
Amps. All fluorescent tests were done using the RAD-VDR module connected to a (2) lamp
Advance Mark VII ballast using T-8 rapid start lamps. These curve plots are to be used as a relative
guide to determining optimum performance. Actual field performance and measurements will be
similar but not equal. FIG. 13shows a basic dimming curve.