CAN.available()

#include <CANBus.h>
unsigned char ch;
void setup() {
    Serial.begin(115200);
    CAN.begin(CAN_500KBPS);
}
 
void loop() {
    if (CAN.requestFrom() > 0)         // Check to see whether data is read
    {
        while (CAN.available() > 0)    // Check FIFO to see whether there are data to be read
        {
            ch = CAN.read();           // Read data from FIFO
            Serial.print(ch);          // Output data content
            Serial.print("\t");
        }
        Serial.println();
    }
}