CalAmp TTU-2830, Руководство по установке оборудования, Страница: 8 / 22

3.5.2 Battery Voltage Critical Input
The TTU-2830™has a built in low battery threshold of 3500mV, which is tied to a
discreet input. If the battery in the device reaches this limit a Low Battery event will be
sent to Actsoft systems.
3.5.3 Ignition and Inputs
The TTU-2830™provides up to 3external inputs. 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 10k
Ω . 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
Ω resistor) or Low (i.e.
pulled to ground through a 10k
Ω
resistor). Input 1 is always biased low, while inputs 2-4
are biased high. The diagrams below show how to connect the inputs in both a high and
low-biased configuration: