Jlg 1230ES Service Manual Manuel d'utilisateur télécharger pdf (Page 31)

SECTION 3 - THEORY OF OPERATION - 1230ES

3121222 – JLG Lift – 3-1

SECTION 3. THEORY OF OPERATION - 1230ES

3.1 OVERVIEW

The GROUND MODULE is the master system controller.

Most functions are dispatched and coordinated from this

module, all other system modules handle sub-tasks. All

characterized information (values) are stored into the

ground module (i.e., Personalities, Machine Setups or

Calibrations). If the ground module is reprogrammed, this

information is lost. The technician should record Personal-

ities and Machine Setups before programming so they

can be restored afterwards. Otherwise, default values can

be used as a starting point to restore previous configura-

tion.

The PLATFORM MODULE reads switch and joystick posi-

tions and relays that information to the GROUND MOD-

ULE. It uses information from the CAN bus for operator

display. It also reports faults pertaining to devices in the

Platform Control Station. In ground mode, the platform

control station may be removed from the vehicle without

affecting operation.

The POWER MODULE controls the main contactor, drive

motors and hydraulic pump motor via commands from

the CAN bus. It also measures current applied to these

loads and input voltage for fault protection and reporting.

For safe operation of the vehicle, the control system will

not allow certain functions under certain conditions. These

are called interlocks. Specific interlocks are discussed

below. The interlocks discussed assume that all control

system devices are functioning properly unless indicated.

Fault conditions will generate DTC’s and additional inter-

locks. Some faults only show up at power-up when the

control system performs a self-test. All controls should be

left alone during this test.

Note that the market and model of the machine affects

what personalities and setups are visible by the Analyzer.

The appropriate information is displayed for the given

model and market. The market and model must be set

properly for safe and lawful operation of the machine.

3.2 MODES OF OPERATION

Ground Mode

In Ground Mode, all visual indicators (LED) in the Platform

are off. In fact, the Platform Control Box may be entirely

disconnected as a normal measure (to secure the vehi-

cle), and this does not prevent Ground Mode operation.

When the machine is powered up in ground mode, only

the functions in the Ground control station are operational,

namely Lift Up and Down. Lift Up and Down is controlled

by a two-position, momentary toggle switch with a center

off position. The switch has the same effect as placing the

joystick in the full up or full down position.

Platform mode

In platform mode the Platform Control Box is enabled. It is

the primary control station for the vehicle. At power-up

indicators applicable to the vehicle configuration illumi-

nate for a lamp check: Battery Discharge Indicator, Sys-

tem Distress Indicator and Tilt Indicator.

3.3 CAN COMMUNICATIONS

CAN (Controller Area Network) is the type of two-wire dif-

ferential serial communication link used between the plat-

form board, ground board, and the power module for

control of the vehicle. This type of network has matured

since its invention in 1986 and is used extensively in many

kinds of machines.

Two-Wire Differential: The signal meaning is derived from

the difference in voltage between two wires, usually

twisted together in a common "jacket". This jacket can

also contain a shield surrounding the wires inside for

noise protection. Any noise that does penetrate the shield

will affect both wires the same. However, the difference in

voltage stays the same, therefore signal meaning is not

corrupted. This differs from one-wire signals in that one-

wire signals derive the signal meaning from the difference

between the signal wire and system ground wire. The sys-

tem ground is the ground for many signals, as well as

power. Any noise on either wire will change the signal and

may corrupt it.

Serial Communication Link: Modules on the link send

messages digitally, bit by bit along the wires where differ-

ent voltage levels represent a "1" or a "0". The 1’s and 0’s

are assembled by the receiver according to the protocol

used to determine the messages meaning. Using serial

communication allows two wires to replace many more. It

also allows use of sensor and switch information in multi-

ple places without duplicating those sensors and

switches.

CAN: On a bus, all modules on the bus are connected to

the same wires. A CAN bus could be represented on a

schematic by a long pair of straight lines with multiple

modules connected to them by short pairs of lines. It has

a termination resistor at both ends of the long lines placed

between the two wires, These resistors are approximately

120 Ohms. On a JLG aerial work platform, this is typically

in the platform and in the chassis. These resistors may be

in the harness or in the module. A complete CAN circuit

measures approximately 60 Ohms between the two wires

and these wires are open to the shield.

Each module on the CAN bus broadcasts its messages

according to a priority assigned to the message. All the

other modules will receive the message and determine if it

is important to them. Typical message traffic is 300 - 500

messages per second. The high bus speed allow all mod-

ules to be constantly updated around 20 times per sec-

ond. A CAN network also has error detection and handling

for robust communications.

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Jlg 1230ES Service Manual Manuel d'utilisateur Page 31

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Jlg 1230ES Service Manual Manuel d'utilisateur Page 31

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