variables {
    message 0xA m1;
            // 0xA is the message ID from your *.dbc can database used in the simulation
    timer timer100;
}

on start {
    timer100.set(100);
}

on timer100 {
    // reset timer
    timer100.set(100);
    // do stuff to your message content
    // for instance m1.signalA = 0x01;
    // ...
    output(m1)  // send m1 on CAN bus
}

on message m2 {
     // ...
}