Jamieson, Fausset and Brown on 1 Chronicles 26:29

29. officers and judges--The word rendered "officers" is the term which signifies scribes or secretaries, so that the Levitical class here described were magistrates, who, attended by their clerks, exercised judicial functions; there were six thousand of them (1Ch 23:4), who probably acted like their brethren on the principle of rotation, and these were divided into three classes--one (1Ch 26:29) for the outward business over Israel; one (1Ch 26:30), consisting of seventeen hundred, for the west of Jordan "in all business of the Lord, and in the service of the king"; and the third (1Ch 26:31, 32), consisting of twenty-seven hundred, "rulers for every matter pertaining to God, and affairs of the king."