Parker PHD28, User Manual, Page: 37 / 157

User Guide 29
Communication
The following table provides specifications for the CAN:
CAN Specifications
Item MIN NOM MAX UNIT
Baud rate limitations (hardware) - - 1000 kbps
Baud rate limitations (software) 125 - 1000 kbps
Wake on CAN current draw - - 500 uA
Termination resistor 120 - -
Ω
6.1.2. J1939 CAN Installation Connections
The CAN connection for the PHD should conform to the J1939 standard. The
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 PHD 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.
▪
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.