How get to value of milage or odometer of each unit?

function getSelectedUnitInfo(){ // print information about selected Unit

    var val = $("#units").val(); // get selected unit id
    if(!val) return; // exit if no unit selected
    
    var unit = wialon.core.Session.getInstance().getItem(val); // get unit by id
    if(!unit){ msg("Unit not found");return; } // exit if unit not found
    
    // construct message with unit information
    var text = "<div>'"+unit.getName()+"' selected. "; // get unit name
    var icon = unit.getIconUrl(32); // get unit Icon url
    if(icon) text = "<img class='icon' src='"+ icon +"' alt='icon'/>"+ text; // add icon to message
    var pos = unit.getPosition(); // get unit position
    if(pos){ // check if position data exists
        var time = wialon.util.DateTime.formatTime(pos.t);
        text += "<b>Last message</b> "+ time +"<br/>"+ // add last message time
            "<b>Position</b> "+ pos.x+", "+pos.y +"<br/>"+ // add info about unit position
            "<b>Speed</b> "+ pos.s+"<br/>"+ // add info about unit speed



            "<b>Odometer</b> "; //THIS VALUE OF MILAGE OR ODOMETER



        // try to find unit location using coordinates 
        wialon.util.Gis.getLocations([{lon:pos.x, lat:pos.y}], function(code, address){ 
            if (code) { msg(wialon.core.Errors.getErrorText(code)); return; } // exit if error code
            msg(text + "<br/><b>Location of unit</b>: "+ address+"</div>"); // print message to log
        });
    } else // position data not exists, print message
        msg(text + "<br/><b>Location of unit</b>: Unknown</div>");
}