CANivore API

All device constructors have an overload that takes a string CAN bus identifier. This identifier can be rio for the native roboRIO CAN bus, * to select the first available CANivore, or a CANivore’s name or serial number. On non-FRC Linux systems, this string can also be a SocketCAN interface.

Note

If there are multiple CANivores with the same name, the system will use the first CANivore found.

If no CAN bus string is passed into the constructor, or the CAN bus string is empty, the behavior is platform-dependent:

• roboRIO: use the roboRIO native CAN bus

• Windows: use the first CANivore found

• non-FRC Linux: use SocketCAN interface can0

Java

TalonFX fx_default = new TalonFX(0); // On roboRIO, this constructs a TalonFX on the RIO native CAN bus
TalonFX fx_rio = new TalonFX(1, "rio"); // This also constructs a TalonFX on the RIO native CAN bus
TalonFX fx_drivebase = new TalonFX(0, "Drivebase"); // This constructs a TalonFX on the CANivore bus named "Drivebase"
CANcoder cc_elevator = new CANcoder(0, "Elevator"); // This constructs a CANcoder on the CANivore bus named "Elevator"

C++ (Header)

hardware::TalonFX fx_default{0}; // On roboRIO, this constructs a TalonFX on the RIO native CAN bus
hardware::TalonFX fx_rio{1, "rio"}; // This also constructs a TalonFX on the RIO native CAN bus
hardware::TalonFX fx_drivebase{0, "Drivebase"}; // This constructs a TalonFX on the CANivore bus named "Drivebase"
hardware::CANcoder cc_elevator{0, "Elevator"}; // This constructs a CANcoder on the CANivore bus named "Elevator"

Python

fx_default = hardware.TalonFX(0) # On roboRIO, this constructs a TalonFX on the RIO native CAN bus
fx_rio = hardware.TalonFX(1, "rio") # This also constructs a TalonFX on the RIO native CAN bus
fx_drivebase = hardware.TalonFX(0, "Drivebase") # This constructs a TalonFX on the CANivore bus named "Drivebase"
cc_elevator = hardware.CANcoder(0, "Elevator") # This constructs a CANcoder on the CANivore bus named "Elevator"

CANBus API

Instead of raw strings, a CANBus object (Java, C++, Python) can be constructed and provided to device constructors. The API can also be used to retrieve information about any given CAN bus, such as the bus utilization.

Java

// create a CAN bus for the CANivore named drivetrain
CANBus canbus = new CANBus("drivetrain");
// construct a TalonFX on the CAN bus
TalonFX fx = new TalonFX(0, canbus);

// retrieve bus utilization for the CAN bus
CANBusStatus canInfo = canbus.getStatus();
float busUtil = canInfo.BusUtilization;

if (busUtil > 0.8) {
   System.out.println("CAN bus utilization is greater than 80%!");
}

C++

// create a CAN bus for the CANivore named drivetrain
CANBus canbus{"drivetrain"};
// construct a TalonFX on the CAN bus
hardware::TalonFX fx{0, canbus};

// retrieve bus utilization for the CANivore named drivetrain
CANBus::CANBusStatus canInfo = canbus.GetStatus();
float busUtil = canInfo.BusUtilization;

if (busUtil > 0.8) {
   std::cout << "CAN bus utilization is greater than 80%!" << std::endl;
}

Python

# create a CAN bus for the CANivore named drivetrain
canbus = CANBus("drivetrain")
# construct a TalonFX on the CAN bus
fx = hardware.TalonFX(0, canbus)

# retrieve bus utilization for the CANivore named drivetrain
can_info = canbus.get_status()
bus_util = can_info.bus_utilization

if bus_util > 0.8:
   print("CAN bus utilization is greater than 80%!")

CANivore Status Prints

When working with CANivore CAN buses in a robot program, Phoenix prints some messages to report the state of the CANivore connection. These messages can be useful to debug connection issues (bad USB vs bad CAN) or report bugs to CTR Electronics.

Connection Messages

Message	Connection Status
CANbus Failed to Connect	Could not connect to a CANivore with the given name or serial number
CANbus Connected	Successfully found and connected to the CANivore with the given name or serial number
CANbus Disconnected	Detected that a CANivore USB device has been disconnected

CANivore Bring-up Messages (Linux only)

Message	Bring-up Status
CANbus Failed Bring-up	Found and connected to the CANivore, but could not configure the device or start the network
CANbus Successfully Started	Successfully configured the CANivore and started the network

Network State Messages

Message	Network State
CANbus Network Down	Linux: The SocketCAN network has been deactivated, USB-to-CAN activity has stopped Windows: Could not open the communication channels for USB-to-CAN traffic
CANbus Network Up	Linux: The SocketCAN network has been activated, USB-to-CAN activity has resumed Windows: Successfully opened the communication channels for USB-to-CAN traffic