Computer Control System; Controller Overview; Inputs; Outputs - Factory Cat MINI-MAG SERIES Service Manual

COMPUTER CONTROL SYSTEM

The Magnum series of machines is equipped with the Central Command II control system.
Central Command II is designed around a very powerful controller that is has a industrial
computer integrated into it. The controller is linked to a Liquid Crystal Display (LCD) to
relay information to the operator or the service technician. The same controller is used in
majority of our equipment, both 24 and 36 volt, but runs a different "program" for each
machine. The controller utilizes unitized construction eliminating many excess components
from the control panel. The switches on the dash board send input signals to the controller.
The controller then interprets the inputs via the program and operates the machine accord-
ingly. The controller has internal protection for both current overload as well as thermal
protection. A large circuit breaker is used on the power feed to the controller for extra
safety against overload. In the event of a malfunction the Central Command II will display
a diagnostic trouble code to aid in the repairing the machine.

CONTROLLER OVERVIEW

INPUTS

The controllers input section uses a technology called tri-state logic to interpret the input
from the switches. The tri-state logic is comprised of low, medium and high voltages. The
inputs have the mid voltage present at them until they are either drawn low or high by a
switch.

OUTPUTS

The controller has a number of outputs and each one of them is electronically protected
from overload. In the event of an overload the machine is shut down by the controller and
a diagnostic trouble code is displayed on the LCD screen. On some of the outputs the
current limit can be adjusted via software to control the amount of current available to the
circuit.

PULSE WIDTH MODULATION

The controller uses a technology called pulse width modulation to control some of the
output circuits. Motors and accessories can be run using this technology in more than one
way. We can change the speed of a motor as well as control the amount of time a valve is
open over one second, such as in our solution system. Pulse width modulation works by
sending pulses of full battery voltage to the device 14,000 times a second. The length of
the pulses determines the speed of the motor. This is a much more efficient way of running
an electrical device at less than 100% operation.

CONTINUITY TESTING

Four of the outputs; traction drive, parking brake, brush & vacuum have a continuity check-
ing feature that monitors the device and the wiring to it from the controller for an open
circuit. This monitoring can be turned on and off for each circuit independently through the
programming of the controller.
Mini-Mag Service Manual V1.0
CENTRAL COMMAND CONTROLLER
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