Factory Cat MINI-MAG SERIES, Руководство по обслуживанию

Страница: 84 / 121

Mini-Mag Service Manual V1.0
13
13-6
CENTRAL COMMAND CONTROLLER
Decide what device there is a request for and how it should operate the device.
TRI-STATE LOGIC
The Central Command II system uses very low voltage throughout it’s control system.
This voltage is less than battery voltage and the controller will be destroyed if battery volt-
age is induced into the control circuits. The tri-state logic uses 3 voltages as follows;
LOW = 0.0 - 0.3 volts
MID = 0.8 - 2.7 volts
HIGH = 4.8 - 5.2 volts
The low and high voltages are reference voltages created by the controller. These volt-
ages are sent to the various controller inputs via the control panel switches. The con-
troller then makes the machine operate a certain way. All inputs at the controller, with
the exception of the throttle input, are at a voltage of 0.8 to 2.6 volts when they are at a
“neutral” or un-switched state. When a signal is sent to an input via a switch it is either a
“LOW” or “HIGH” reference signal. The computer monitors the input terminal many times
a second and when the voltage of it changes the computer reacts accordingly to the pro-
gram in it changing the outputs of the controller.
INPUTS- VARIABLE VOLTAGE
It addition to the standard tri-state logic inputs the controller also used varied voltage
inputs. Examples of these inputs would be the throttle and the solution circuit. On these
inputs the a high and low signal are fed to a 5K potentiometer on each of the outside
terminals. The voltage is summed by the potentiometer and the summed voltage is sent
out the center terminal of the potentiometer to the input terminal on the controller. As
the potentiometer is rotated the center wiper contact inside increases or decreases it’s
distance from the high reference signal creating a sweeping voltage from about 0.0 volts
to 5.1 volts. This sweeping voltage is interpreted by the controller and the outputs are
then controlled according to the program.
OUTPUTS
The outputs of the controller are controlled by the embedded computer and its program.
It iterprets the inputs and energizes the out puts accordingly. The outputs on the control-
ler are driven by transistors and not relays so they are different to diagnose than a tradi-
tional control system. An important thing to be aware of is when an output is turned off
there can be as much of 80% of the voltage present at the output when you measure it
with a meter. The voltage that is present comes from the continuity test that the control-
ler continually runs on some of the output circuits. This a very low amp signal that can
register on your meter but is not enough amperage to power a motor or other accessory.
To consider an output to be “on” or activated it must be 95% of battery voltage.
SOLUTION SOLENOID: AUX 3
The solution solenoid output of the controller provides a ground to the solution solenoid
valve. The positive voltage feed to the solenoid valve comes from the switched B+ power
from the controller on pin #8 of the 14 pin Molex connector at the controller.