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Chapter 3: 955QD Overview
3.5: Features
Automatic Gain Control
The Automatic Gain Control feature is only used when sensing a magnet other than the standard SD0521800
slide magnet. If you are using the standard slide magnet, skip this operation.
When using the Floating Magnet assembly (SD0522100), the magnet should be installed within 3/8" of the
sensing surface. The magnet assembly should also be installed in such a manner that it remains an even
distance from the aluminum extrusion throughout the entire stroke. Improperly installed magnets can result
in output signal non-linearity.
To set the Automatic Gain Control (AGC) level for the probe follow these steps.
NOTE: Before starting, it is important to determine the input type of the LDT in question. On input type
"E" or "T"" take input pins 8 and 9 to pin 2 (Input Power). On input type "C" take input pins 8 and 9
to pin 1 (common).
1. Place magnet assembly close to the dead zone (but within the active region) of the probe.
NOTE: The north pole of the magnet should always be pointed towards the probe.
2. Power down the probe.
3. Short "BURST IN" (pin 8) and "ZERO INPUT" (Pin 9) to ground (Pin 1) for input type "C"
or to input power (pin 2) for input type "E" or "T".
A. Apply power to the probe, the LED ashes Yellow and Red for one second
B. The LED will change from ashing yellow and red to ashing yellow and green once it has
found the magnet.
NOTE: If the LED never changes to ashing yellow and green; the magnet signal is too weak. Remove power
from the LDT and move the magnet closer.
NOTE: When the probe is in AGC mode, the output will be inactive.
The AGC is now complete.
To place the probe back into the normal operating mode follow these steps:
1. Power down the probe
2. Remove "BURST IN" pin (Pin 8) and "ZERO INPUT" pin (Pin 9) from power or ground.
3. Apply power to the probe.
The probe is now in the normal operating mode.
LED Colors
Green: Magnet is present and within the active range.
Red:
Fault, the LDT has lost its signal from the magnet or the magnet has moved into the Null or
Dead Zone.
Yellow: The LDT is in the AGC mode, yellow appears in short bursts combined with either red or green
when in the AGC mode.
11
Installation, Programming and Maintenance Manual
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