JLG X20JP - X600AJ Service Manual - Manual (Page 226)

SECTION 6 - JLG CONTROL SYSTEM
6-10 – JLG Lift – 3121623
6.3 CANBUS COMMUNICATIONS
The electrical system works with a CAN BUS system,
where:
CAN = Control Area Network
BUS = Channels for peripherals
CANbus: CAN (Control Area Network) is a two wire differ-
ential serial link between the, Ground Module ECM1-2; the
Remote Control; the LSS ECM3, the Cylinders position
sensors and the Rham Modem Module providing bi-direc-
tional communications.
Two-wire: One wire (White; Black or Black with numbers)
is driven high (5v) and the other low (Gray; Brown or Black
with number) (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 speeds allow all modules to be con-
stantly updated around 20 times per second. Typical traf-
fic is 300 - 500 messages per second.
A complete CANbus circuit is approximately 60 ohms,
Each individual circuit from the modules is approximately
120 ohms.
The GROUND MODULE ECM1-2 is the master system
controller.
Most functions are dispatched and coordinated from this
module, all other system modules; Remote Control; LSS
ECM3; Cylinders position sensors; Rham Modem.
Fundamental characterized information (values) are
stored into the ground module ECM 1-2 (i.e., Personalities
or Calibrations), while on the LSS ECM3 the basket load
setting.
Lift, Tele, Swing & Drive:
The GROUND MODULE ECM1-2 stores default values,
handles interlocks and calibration information.
Lift, Telescope Swing and Drive commands are depen-
dent upon interlocks through out the machine that
enables the power supply of the ON -OFF proportional
coils after verification of the safety conditions by handles
interlocks.
The safety control functioning ECM1 can be by - passed
by the key selector switch (spring return) “safety device
by-pass key”.
The circuit board ECM1 record any by-pass event by date,
time and duration of the “safety device by-pass key”
action.