if(prev_edge != edge != 0) /* edge type has changed */
    {
        prev_edge = edge;
        prev_trigger = !edge;
    }
    if(force != prev_force) /* force type has changed */
    {
        prev_force = force;
        if(force && (trigger == edge))
        {
            show = true;
        }
    }
    if(trigger != prev_trigger) /* trigger has changed */
    {
        prev_trigger = trigger;
        if(trigger == edge)
        {
            show = true;
        }
    }
    if(show && messages[myidx] != 0)
    {
        rtapi_print_msg(RTAPI_MSG_ERR, "%s\n", messages[myidx]);
    }