JLG 600SC_660SJC Service Manual - Manual (Page 229)

SECTION 6 - JLG CONTROL SYSTEM
3121607 – JLG Lift – 6-35
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