After the oath is administered to the members of the grand jury, the judge shall charge them orally in open court upon their duties, rights, and powers.  Upon completion of the charge the judge shall give the grand jury a written copy of the charge.

At any time thereafter, the judge, on his own initiative or on request of the grand jury, may give the grand jury additional charges concerning their duties, rights, and powers.  Such additional charges shall be given in open court, and a written copy thereof shall thereafter be given to the grand jury.