Except as otherwise provided in this article, no person shall carry a pistol about his person on private property not his own or under his control unless the person possesses a valid concealed weapon permit or the person has the consent of the owner or legal possessor of the premises; but this section shall not apply to any law enforcement officer in the lawful discharge of the duties of his office, or to United States marshal or his deputies, rural free delivery mail carriers in the discharge of their duties as such, bonded constables in the discharge of their duties as such, conductors, railway mail clerks and express messengers in the discharge of their duties.