Minimum wages are fixed by the appropriate Governments u/s 3(1)(a) of the Minimum Wages Act,1948 in respect of the scheduled employments as soon as they are included in the schedule.
Once fixed thus, they are reviewed once in 5 years and revised accordingly u/s 3(1)(b) of the Act.
The revision which is made once in 6 months as referred to by you is the upward revision of the dearness allowance according to the hike in the Cost of Living Index to which the D.A is linked.
The threshold for P.F contribution is Rs.15000-00 as of now. If the calculation is made on the basis of the threshold limit, you need not bother about total revision of the minimum wages or the periodical revision of the amount of dearness allowance in tune with the rise in the relevant C.L.I.