An exercise system using a door frame has a cylindrical bar perpendicularly located between a first jamb and a second jamb. The on-line diagnostics systems comprises industrial equipment and a maintenance apparatus for the maintenance of the industrial equipment, which are connected via the Internet. The purge chamber is defined by a purge chamber bulkhead. A beam pitch-detecting device is also provided so as to detect a beam pitch of the respective beams formed on the scan-receiving surface.