Parker PSVG-IQAN-C2E1M2W1U1, Руководство пользователя

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27
Communication
The following lists the elements that are required for a J1939 CAN
connection:
▪
CAN Cable: A shielded twisted-pair cable should be used when
connecting multiple modules to the CAN bus. The cable for the J1939
CAN bus has three wires: CAN - High, CAN - Low, and CAN Shield
(which connect to the corresponding CAN_HIGH, CAN_LOW, and
CAN_SHIELD pins on the connector). When a module does not have a
CAN_SHIELD pin, the CAN Shield should be connected to an
available ground terminal attached to the negative battery. The CAN
cable must have an impedance of 120 Ω.
▪
CAN Connectors: Industry-approved CAN connectors are
manufactured by ITT Cannon and Deutsch, and come in either T or Y
configurations.
▪
CAN Harness: The CAN harness is the main backbone cable that is
used to connect the CAN network. This cable cannot be longer than 40
meters
and must have a 120 Ω terminating resistor at each end
.
The 120 Ω terminating resistors eliminate bus reflections and ensure
proper idle-state voltage levels.
▪
The CAN cable is very susceptible to system noise; therefore, CAN
shield must be connected as follows:
a. Connect CAN Shield to the point of least electrical noise on the
CAN bus.
b. Connect CAN Shield as close to the center of the CAN bus as
possible.
c. Use the lowest impedance connection possible.