How to Run MRP in SyteLine
How do I run MRP in SyteLine?
Also searched as
- SyteLine MRP net change vs regenerative
- SyteLine MRP action messages explained
- how to read SyteLine MRP detail
- SyteLine MRP not generating planned orders
Short answer
MRP in SyteLine runs from Planning > MRP Processing as either a full Regenerative run or a Net Change run against demand from customer orders, forecasts, and safety stock; results appear as planned orders and Action Messages in the Planner Workbench.
Applies to: SyteLine 8.x/9.x, CloudSuite Industrial (CSI) 10.x-11.x, Mongoose and classic UI
Run MRP in SyteLine
- 1Confirm demand inputs are current: customer order lines released, forecast loaded, and safety stock/reorder parameters set on item records.
- 2Open Planning > MRP Processing and choose scope: single site or all sites.
- 3Choose Regenerative (full recalculation) or Net Change (only items with changed demand/supply since the last run).
- 4Set the planning horizon and any item or site filters if you are not running the full plan.
- 5Run MRP and monitor the log for errors, such as items with no valid vendor or routing that block a planned order suggestion.
- 6Review Action Messages (Reschedule In, Reschedule Out, Cancel, New Order) in the Planner Workbench or Action Message report.
- 7Review the planned orders generated for purchased and manufactured items.
- 8Firm and release the planned orders you accept: purchased items become requisitions or POs, manufactured items become job orders.
- 9Re-run Net Change MRP after significant transactions, such as a large order entry, receipt, or job completion, rather than waiting for the next scheduled regenerative run.
Regenerative vs Net Change
A Regenerative run recalculates the entire plan from scratch across every planned item, which is heavier on the database and is typically scheduled overnight or over a weekend on larger sites. A Net Change run only reprocesses items whose supply or demand actually changed since the last run, which is light enough that planners can trigger it intraday whenever they need an up-to-date plan.
Most sites run Net Change several times a day and schedule a full Regenerative run weekly or nightly to catch any drift that incremental Net Change runs can accumulate over time.
What drives a planned order
MRP nets independent demand (forecast and safety stock) plus dependent demand (the BOM explosion coming down from parent planned or released orders) against on-hand quantity and on-order supply, then applies each item's lead time and lot-sizing rule to decide when and how much to suggest. The result is a planned order with a suggested start date, due date, and quantity for every item where the net requirement is greater than zero.
Reading the Action Messages
New Order tells the planner MRP wants a new purchase order or job order created. Reschedule In means an existing order should be pulled in earlier because demand moved up. Reschedule Out means an existing order can be pushed later because demand moved out, which frees up cash and floor space if acted on. Cancel means the underlying demand for an existing order disappeared entirely and the order should be reviewed for cancellation.
Each message type expects a specific planner response, and letting messages sit unactioned for multiple runs is what causes MRP output to feel noisy rather than actionable.
Why MRP doesn't suggest an order
If an item that should be generating a planned order is not, the usual causes are the item being incorrectly flagged as non-planned or phantom, a missing primary vendor or routing that leaves the system unable to build a valid suggestion, or the item's planning method being set to something other than MRP, such as a simple min/max reorder point that MRP does not process the same way.
Common pitfalls
- !Running a full Regenerative MRP during business hours on a large multi-site database can lock tables and slow order entry for other users.
- !Net Change MRP run too infrequently lets action messages go stale, so planners end up acting on outdated suggestions.
- !Lead time set at zero or unrealistically low on purchased items causes MRP to generate late or physically impossible ship dates.
- !A phantom BOM item incorrectly flagged as a stocked item breaks the explosion logic and generates a false planned order.
- !Ignoring Reschedule Out messages leaves excess WIP and inventory tied up that MRP already identified as no longer needed on the original schedule.
- !Assuming a single-item test run behaves identically to a full regenerative run when shared components or capacity constraints are involved.
How an ERP-grounded AI assistant handles this
ERPray can summarize the day's MRP action messages in plain language - these purchased items need expediting, these job orders should push out - grounded directly in the SyteLine planning tables, cutting the time a planner spends scrolling the Planner Workbench line by line each morning.
Frequently asked questions
How often should MRP run?
Most sites run Net Change MRP daily or even multiple times a day, and schedule a full Regenerative run weekly or nightly during a low-activity window to catch any drift that has built up from the incremental Net Change runs.
Why does MRP keep suggesting the same reschedule message every day?
Usually the planner has not actually actioned the underlying order yet, such as moving the PO date or firming a job order, or the item's lead time and lot-size setup causes the same suggestion to regenerate identically on every run until something changes.
Can I run MRP for a single item?
Yes, most SyteLine versions support a single-item or filtered MRP run, which is useful for testing the effect of a data change without triggering a full regenerative pass across the whole plan.
What is the Planner Workbench used for versus the Action Message report?
The Planner Workbench is the interactive screen where a planner reviews and acts on messages and planned orders item by item. The Action Message report is a printable or exportable summary better suited for a review meeting or handing planning priorities off to buyers.
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