Error trying to display data from 2 tables using php and mysql

I'm having an error trying to show data from two tables. Error: Warning: Invalid argument supplied for foreach () in C: \ xampp \ htdocs \ Frank \ principal.php on line 45

            <?php
            $consulta= "SELECT CONCAT(nombre,' ',apellido) AS nombre, numOrden, problema,  modelo,  fecha, estado FROM orden, usuario WHERE orden.idUsuario=usuario.id ";

                foreach ($conex->query($consulta) as $row){ ?> 
                <tr>
                    <td><?php echo $row['numOrden']?></td>

                    <td><?php echo $row['nombre']; ?></td>
                    <td><?php echo $row['estado']; ?></td>
                    <td><?php echo $row['modelo']; ?></td>
                    <td><?php echo $row['problema']; ?></td>
                    <td><?php echo $row['fecha']; ?></td>
                 </tr>
                <?php
                    }
                ?>
                </table>