MRP-NAV-LOGIC-Re-Order Cycles -NAV 2009

Does NAV ONLY plan demand within a reorder cycle? (Reorder cycle = period) Assume MRP was run OCT 10

Period 1 = Oct 10-Oct 16

Period 2 = Oct 17-23

IF there is a release PO (Flexible is NOT set to NONE) due Oct 12 and the original demand moved from OCT 12 to OCT 20 (Next Reorder Cycle) will MRP cancel the current released PO from the current period and suggest a new PO for the other period? Qty of the demand has not changed; the only thing that changed is the date which moved to a new period.

I have reworded the post

All I need to know is if this represents the logic that NAV uses

I tried to word it so that the answer is a simple yes or no

Thank You



That is good news

Sorry for a possible dumb question, Adam are you a Microsoft support person?

So back to my original post

Is there a BUG in NAV 2009 or is it a setup?

Hi Dave

No I am not a Microsoft support person, but the company you are advising should have access to a partner support network and therefore access to Microsoft, but the partner should be able to assist.

In my opinion it is setup, but as I said before it has been a long time since I looked at NAV, but I never had this issue pre-2009. Basically if there was, for example, a requirement on 11-10-11 and you moved the demand to 21-10-11 even with a 7 day reorder cycle it would suggest a reschedule because the original demand is no longer present.

If i had access to the software I could set this up as a simple test, it would only take 5 minutes, but I no longer have access to the software.

The other alternative is the partner has modified the planning engine.

Thanks for your comments

I did test things and this is the way it is working

As mentioend I do not setup NAV

I am in touch with the dealer

I have also requested a direct contact with Microsoft


hi Dave,

I would disagree with Adam’s post. It is how NAV works.

So, as a one word answer, the answer is “yes”.

The concept being that the reorder cycle is a time period within which you want to group the supply and demand calculations for NAV. If NAV cannot see any demand in the period (i.e. the next month) but can see supply, then it’s logic will say that the supply is uneccessary and therefore cancel it.

As for the following period, NAV will see demand, but no supply, so suggest a new order quantity.

What you end up with is a series of Cancel/New messages, much to the user’s annoyance.

You’re option is to change the re-order cycle (i.e. make it a longer time period), or modify the inventory offset profile codeunit (which is like trying to hit fly with your eyes closed), or create a new function which accepts the MRP message and then goes through a further logic step to cleanse the NAV message.

My memory tells me the difference between the actual cancel/new and rescduling was based in part upon the flexibility settingbeing none, or another setting, so we would get this, change the setting and then you would get rescehdule messages. However this was also dependent upon the Planning Worksheet and Production being used. Anyway this was the way it worked in version 4 and before, but as I said I have no access to 2009 and have not used it for a long time, so if this is now the way it works it is fine by me [:D]

no probs, wasn’t trying to pick holes, just disagreeing with your viewpoint.

The whole NAV MRP code has a view warped bits of logic, which work for an IT developer, but not for an MRP planner, and this unfortunately is one of them.

No I would prefer not to answer something with outdated knowledge, would much rather someone with current access would answer.

If I had the software, time and inclination I would have looked at the software, but I have none of this, which is also reasons for the several caveats I post.

As it now does not do this I will realign my viewpoint [:D]