MRP with firm plan orders scenario.

Dear all,

we are in process of MRP implementation.

where client having every month a plan of Three months in which first month plan is fixed whereas two months are tentative.

to achieve this we have used Planning time fence of 38 days as we run MRP on 22 of every month.

On next month we have to inactivate first plan and create anew plan ,I wanted to MRP Run for new plan with last firm orders. But is found that

when we run MRP,the plan qty of 22 to 30 date has been reducing Plan qty of next month.whereas we want 22 to 30 qty(e.g. say 100 Nos)should be as it is and also suppose next months Plan is 500 qty then it should have to create plan orders for next month as qty 500.and not as 400 Nos

Planning strategy is 11 as gross planning and PIR consumption at the time of Goods reciept.

Regards,

Pravin K.