SECTION 6 - JLG CONTROL SYSTEM
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6.4
CANBUS COMMUNICATIONS
CANbus: CAN (Control Area Network) is a two wire differential
serial link between the Platform and Ground Modules provid-
ing bi-directional communications.
Two-wire: One wire (red) is driven high (5v) and the other low
(black) (0v) to send a signal. Both wires ”float” (2.5v) when no
signal is being sent.
Differential: Any electrical line noise can affect the high or the
low wires but never both, so communications is not corrupted.
Serial Link: Messages are being sent bit by bit along the wires;
the high bus speed allow all modules to be constantly
updated around 20 times per second. Typical traffic is 300 -
500 messages per second.
A complete CANbus circuit is approximately 60 ohms, which
can be verified at the”T” fitting inside the ground station. Indi-
vidual circuits are approximately 120 ohms.
The GROUND MODULE (UGM) is the master system controller.
Most functions are dispatched and coordinated from this
module. The PLATFORM MODULE handles sub-tasks. All char-
acterized information (values) are stored in the ground mod-
ule (i.e., Personalities or Calibrations).
Interlocks:
Any device that sends an electrical input. (For an
example a limit switch, proximity switch, etc.
Platform Level: The GROUND MODULE stores default values
and handles interlocks. The PLATFORM MODULE reads sensors
mounted on the platform assembly and controls Level Up /
Down valves to maintain setpoint sent from the GROUND
MODULE.
Steer: The GROUND MODULE stores crack points, and sends
desired drive direction, steering mode, and axle extend/retract
commands. The PLATFORM MODULE reports steering switch
position to the GROUND MODULE.
Drive: The GROUND MODULE stores crack points and sends
commands for each drive pump. (Command is computed from
drive joystick input, interlocks, wheel angle, etc).
Lift, Tele, & Swing: The GROUND MODULE stores default val-
ues, and handles interlocks and calibration information. Lift,
Telescope, and Swing commands depend on interlocks
through out the machine. Boom angle, length, and swing are
controlled by the GROUND MODULE.
6.5 MSSO (MACHINE SAFETY SYSTEM OVERRIDE)
The MSSO (Machine Safety System Override) fitted to the
ground console and is standard only for the CE market. The
MSSO is only used to retrieve an operator who is pinned,
trapped, or unable to operate the machine from the platform
controls and function controls are locked out from platform
due to a platform overload situation.
Platform overload fault is logged like any other fault, it remains
active and is displayed until it is removed using the JLG Ana-
lyzer.
No functional checks of the MSSO system are necessary. The
JLG control system will set a Diagnostic Code if the MSSO
enable switch is faulty.
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