Welcome back to our Dynamics GP vs. Dynamics Business Central Functionality Face-Off. This is Round 42. Last round we followed a production order from release to finish. But before you can run an order, someone has to answer the two oldest questions in manufacturing: what should we make, and what should we buy?
That is material requirements planning — MRP. Both systems have it. The difference is when you get your answers, and how much work it takes to act on them.
How you do it in Dynamics GP
GP’s MRP lives in the Manufacturing module, and it runs as a scheduled batch process.
- Set up MRP defaults. Open the MRP Preference Defaults window (Microsoft Dynamics GP menu >> Tools >> Setup >> Manufacturing >> System Defaults >> MRP). Here you choose which suggestion types GP generates — including whether to suggest moving in, moving out, or canceling purchase orders and manufacturing orders (Microsoft Learn).
- Schedule the regeneration. In the Schedule MRP window, you set up when MRP recalculates — a full regeneration or a lighter net-change run. Most GP shops schedule the full regeneration overnight, because it rebuilds the whole plan (Microsoft Learn).
- Review the suggestions. After the run, planners review the results in GP’s MRP inquiry windows and workbench. GP compares the projected available balance at each item and site and suggests new orders, move-ins, move-outs, and cancellations (Microsoft Learn).
- Act on them by hand. The suggestions are advice, not documents. To follow one, you go create or change the purchase order or manufacturing order yourself. And GP has rules about what it will suggest: for example, it will suggest a brand-new purchase order instead of moving in an existing one if that order’s status is not on the accepted list — and that is by design (Microsoft Learn).
There is also a second, separate tool: the purchase order generator in Purchase Order Processing, which suggests POs for buy items based on reorder points (Microsoft Learn). So planning advice can come from two places that do not know about each other. And when the overnight regeneration hangs — down-day restrictions, low-level codes, a recursive BOM — the fix list involves database tables (Microsoft Learn).
How you do it in Business Central
Business Central puts planning in a worksheet you run whenever you want.
- Set the rules on the item. Each item (or stockkeeping unit) carries a reordering policy — Fixed Reorder Quantity, Maximum Quantity, Lot-for-Lot, or Order — plus lead times and safety stock. The policy tells the planning engine how to react to demand (Microsoft Learn).
- Open the Planning Worksheet and calculate. Choose Calculate Regenerative Plan to rebuild the full plan, or a net-change run for just what moved. You can calculate MPS, MRP, or both in one pass — on demand, right now, not at 2 a.m. (Microsoft Learn).
- Read the action messages. The worksheet fills with lines, each carrying an action message: New, Change Qty., Reschedule, Reschedule & Change Qty., or Cancel. Demand and supply are netted for you, line by line (Microsoft Learn).
- Accept and carry out. Tick Accept Action Message on the lines you agree with, then choose Carry Out Action Message. BC creates the actual documents — purchase orders, production orders, transfer orders — in one step. No retyping.
For purchase-only businesses, the same engine runs in the Requisition Worksheet: Calculate Plan, review, carry out — and your purchase orders appear (Microsoft Learn). One planning engine covers make, buy, and transfer, so all the advice lands in one place (Microsoft Learn).
Side by side
| Task | Dynamics GP | Business Central |
|---|
| Task | Dynamics GP | Business Central |
|---|---|---|
| When the plan runs | Scheduled batch regeneration, often overnight | On demand from the worksheet, any time |
| Where advice appears | MRP inquiries and workbench, plus a separate PO generator | One planning engine: Planning and Requisition Worksheets |
| Types of advice | New orders, move in, move out, cancel | Action messages: New, Change Qty., Reschedule, Resched. & Chg. Qty., Cancel |
| Acting on advice | Create or change each PO/MO yourself | Accept lines, Carry Out — documents created automatically |
| Item planning rules | MRP preferences plus reorder points in POP | Reordering policies, lead times, safety stock on the item card |
| When it breaks | Regeneration hangs can need table-level fixes | Rerun the worksheet |
Why BC comes out ahead
Credit where due: GP’s MRP does real gross-to-net planning, and its move-in, move-out, and cancel suggestions were genuinely ahead of their time. Shops that schedule it well get solid answers every morning.
But those answers are stale by lunch, and every suggestion still becomes manual work — a purchase order to key, a manufacturing order to reschedule. Business Central closes both gaps. The plan runs when you ask, the advice arrives as action messages you can sort and filter, and Carry Out turns your decisions into real documents in one click. Planning stops being a nightly report you react to and becomes a tool you drive.
Ready to plan on demand?
If your planners spend mornings retyping MRP suggestions into purchase orders, we should talk. Aisling Dynamics helps GP manufacturers map their MRP settings onto Business Central reordering policies so the worksheet gives answers they trust. See what we offer, then contact us or call (251) 293-0555 for a no-pressure conversation.
Next up in Round 43: project accounting — GP Project Accounting vs. Business Central Projects, from job tasks to WIP.