9-M7
L3130 · L3430 · L3830 · L4630 · L5030, WSM
ELECTRICAL SYSTEM
2. ELECTRONIC CONTROL PANEL
[1] SYSTEM OUTLINE AND ELECTRICAL CIRCUIT
(1) System Outline
W1012906
The Electronic Instrument Panel (IntelliPanel) adopted in the L30 series tractors consists of an 8-bit Central
Processing Unit (CPU
*1
), sensors and input devices, memory devices such as RAM and ROM, and others. The CPU
executes multiplex-communication
*2
with ECU (Electronic Control Unit) and various sensors, switches and other
related devices in order to give the functions that accurately and timely provide an operator with various information
necessary for tractor operation. The contents include corrective procedure in case of an erroneous operation,
precautions, and various alerts. If the tractor gets in trouble, a defective location, for example, is displayed with a
message (sign) on the liquid crystal display (LCD
*3
) or indicated with a monitor lamp.
The messages are displayed with segments, which gives approximately 130 patterns.
In the LCD, characters appear over reflected illumination, and are always back-lit by a small yellow lamp while the
main switch is “ON”.
*1
CPU
This CPU is the core part of computers that controls the input/output devices to receive data, processes the data,
and sends out the computing results.
The CPU comes in different types : 8 bits, 16 bits, 32 bits, etc., according to the number of bits as the unit of internal
data processing. In general, the larger the number is, the higher the performance is.
*2
Multiplex communication
In multiplex communication, just one transmission (signal) line is effectively used to send and receive signals for
digital transmission. In data communication, the transmission capacity of the line and the capacity of signal
transmission/reception are represented by the number of bits that can be transmitted or received for one second.
When the capacity of the transmission line is extremely larger than the ability of the transmission/reception performed
by a terminal device, signals from plural terminals can be transmitted by means of time-sharing and multiplexing of
one transmission path.
The merits of multiplex communication are as follows :
1. It permits high-performance control that allows three units to share information from sensors and information
required for control.
2. It provides the smaller number of wire harnesses.
3. It allows each control unit to independently control the connected devices if communication should fail for some
reason and become impossible.
*3
LCD
LCD is a displaying device that utilizes the characteristic of liquid crystal, in which the application of voltage triggers
the molecules to change their orientations. The principle of indication is that when a voltage is applied on a liquid
crystal sandwiched between two glass plates, the direction of molecules changes, with the resultant variation of the
oscillatory direction of light that penetrates the liquid crystal. The set-up of a polarizing plate makes light go through
or get blocked according to a change in voltage. Since the use of only the polarizing plate results in peculiar color,
the film to counteract colored light is superimposed. However, the liquid crystal it self does not generate light, so it is
back-lit by a fluorescent tube, for example, which makes the display easy to read in a dark space.
(1) Combination Switch
(2) Liquid Crystal Display (LCD)
(3) Electronic Instrument Panel
(IntelliPanel)
(4) Hazard Switch
(5) Travel Speed Switch
(6) Display Mode Switch
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