Parker PVSG-IQAN-C2E1M2W1U1, Руководство пользователя, Страница: 46 / 70

37
Communication
7.1.2. J1939 CAN Installation Connections
The CAN connection for the PVSG-IQAN should conform to the J1939 standard.
The SAE J1939 standard is a robust automotive specification that is a good CAN
installation guideline even when the J1939 CAN protocol is not being used.
For a list of J1939 connection considerations, refer to the SAE J1939 specifications
available through the Society for Automotive Engineers. SAE J1939-11 covers the
physical aspects of the CAN bus including cable type, connector type, and cable
lengths.
Note: The standard variant of the PVSG-IQAN does not have a CAN
termination resistor, which is based on the assumption that the CAN bus
is terminated in the harness.
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 ea ch 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.