CAN Bus interface

Provides a software interface to the CAN BUS. Internally this objects uses the SocketCan interface.

Object

class IQData {
     constructor CanBus();
     bool open( String interface );
     bool close();

     bool send( can_id , data : array of integers );
     Object receive( can_id );
}

.open

Opens the specified CAN interface. Returns false if the interface is not available or cannot be opened.

.close

Closes (releases) the CAN interface previously opened.

.send

Send data to the CAN Bus.

    bool send( can_id , data : array of integers );

Returns true if the provided data has been sent.
Parameters :

can_id : the CAN ID to be used for this message,
- bit 0-28 : CAN identifier (11/29 bit)
- bit 29 : error message frame flag (0 = data frame, 1 = error message)
- bit 30 : remote transmission request flag (1 = rtr frame)
- bit 31 : frame format flag (0 = standard 11 bit, 1 = extended 29 bit)
data : an array of integers. The length of the given array is used to set the frame length.

.receive

Waits for data. This is a blocking call.
```
    Object receive( can_id );
```

Returns an object with the following structure :

    {
        "send_to": <CAN ID of the sender>,
        "data":[ array of integers]
    }

Example

For a background on CAN Bus under linux, see :

How To Use SocketCAN With The Command-Line In Linux

/* Can bus example 
   to test under linux with no CAN phyiscal interface , we use vcan0
   setup :
   sudo ip link add dev vcan0 type vcan
   sudo ifconfig vcan0 up
*/

var interface_name = 'vcan0' ;

var bus = new CanBus();
print('Opening interface...');

if( bus.open(interface_name) === false ) {
    print('Cannot open interface ['+interface_name+']') ;
    exit();
}


// Test send data
// under linux, data can be monitored using tools from package :
// sudo apt-get install can-utils
// then :
// candump vcan0
var data = new Array();
data[0] = 0x01 ;
data[1] = 0x02 ;
data[2] = 0x02 ;
bus.send(0xf1,data) ; // candump will display : vcan0  0F1   [3]  01 02 02

// Test receive
// under linux , for example :
// cansend vcan0 002#0102030405
var x = bus.receive(0x02) ;
print( JSON.stringify(x));
// with given example, will print : {"send_to":2,"data":[1,2,3,4,5]}

Last update: January 8, 2022