Ignition And Inputs - Cal Amp LMU-2x30 Hardware And Installation Manual

LMU-2x20™ Hardware and Installation Guide

4.4.1 Ignition and Inputs

The LMU-2x30™ provides up to 5 external inputs and one internal. The external inputs are
protected from typical vehicle transients and can be directly connected to most vehicle level
logical inputs from 4 volts up to the vehicle power input level (typically 12 VDC). Their
input impedance is approximately 10kΩ. One of these inputs is dedicated to sensing the
vehicle's ignition status to provide for flexible power management. The other two inputs
may be used to sense vehicle inputs such as cooling unit operation, a hidden driver "Panic"
switch, taxi on-duty/off-duty meter status or many others.
The ignition input is pulled to ground through the 10k resistance, where the other inputs can
either be normally High (i.e. pulled to +12v through a 10k resistor) or Low (i.e. pulled to
ground through a 10k resistor). Input 1 is always biased low, inputs, 2-4 are biased high The
diagrams below show how to connect the inputs in both a high- and low-biased
configuration:
V1.0.10 December 12, 2010
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