Preactor did not disappear. It became Siemens Opcenter APS

If you search for Preactor today, you will probably encounter pages for Siemens Opcenter APS instead.

That is not a different product family appearing in your search results by mistake.

Preactor was a well-known Advanced Planning and Scheduling, or APS, software product. Siemens acquired Preactor in 2013 and later incorporated it into its broader Manufacturing Operations Management portfolio. The product was eventually rebranded as Siemens Opcenter APS.

Preactor production scheduling software now known as Siemens Opcenter APS

So the simplest answer is:

Preactor is the former name of what is now Siemens Opcenter APS.

Many manufacturers, consultants and longtime users still use the Preactor name, which is why you will continue to see both names online. Even Siemens partners commonly describe Opcenter APS as formerly Preactor.

Preactor → Siemens Opcenter APS

The name changed over time, but the software’s core purpose remains recognizable.

A simplified history looks like this:

Preactor APS
↓
Siemens Preactor / SIMATIC IT Preactor APS
↓
Siemens Opcenter APS

Siemens announced the Opcenter APS branding as part of a broader Manufacturing Operations Management rebranding effort. Siemens described Opcenter APS as the advanced planning and scheduling solution formerly known as Preactor APS.

That explains why older manufacturing documentation, consultants, users and search results may still refer to Preactor while newer Siemens material uses Opcenter.

What Did Preactor Software Do?

Preactor was designed to help manufacturers create realistic production plans and schedules.

That sounds straightforward until you compare it with the way many production schedules are actually created.

A basic production plan might say:

  • Make 500 units this week.
  • Run Job A before Job B.
  • Finish everything by Friday.

But factories have constraints.

A particular machine may already be busy.

A tool may only be available on one line.

An operator may not be scheduled.

A material shipment may arrive late.

Changing from one product to another may require a long setup.

Two operations may need to happen in a particular sequence.

A rush order may suddenly become the highest priority.

Preactor was designed to account for those real-world constraints when creating production schedules.

That is what Advanced Planning and Scheduling software is intended to do.

What Is APS?

APS stands for Advanced Planning and Scheduling.

APS software helps manufacturers determine what should be produced, when it should be produced and which resources should be used, while considering the actual limitations of the factory.

Those constraints can include:

  • Machine capacity
  • Labor availability
  • Material availability
  • Tooling
  • Setup and changeover time
  • Shift calendars
  • Operation sequences
  • Due dates
  • Production priorities
  • Maintenance
  • Bottlenecks
  • Business rules

Modern Opcenter APS uses finite-capacity planning and scheduling to balance manufacturing demand against available capacity and constraints.

The phrase finite capacity is important.

What Is Finite-Capacity Scheduling?

Imagine three production orders all require the same machine tomorrow.

That machine can only run one operation at a time.

A scheduling system that assumes unlimited capacity might produce a plan in which all three orders appear to run simultaneously.

Unfortunately, the machine has not received that memo.

A finite-capacity scheduling system recognizes that the machine only has a certain amount of available time.

It schedules work around the capacity that actually exists.

The same principle can apply to:

  • Machines
  • Production lines
  • People
  • Tools
  • Work centers
  • Materials
  • Other limited resources

That is one of the main reasons manufacturers use APS instead of relying entirely on spreadsheets, basic MRP calculations or manually maintained schedules.

Is Preactor the Same as Opcenter APS?

Broadly, yes.

Preactor APS evolved into Siemens Opcenter APS.

Siemens partners that specialize in the product still explicitly connect the two names. Neo Digital Industries describes Opcenter APS as the renamed successor to Preactor following Siemens’ 2013 acquisition, while ATS Global identifies Siemens Opcenter APS as formerly Preactor.

However, that does not mean today’s Opcenter APS is identical to a Preactor installation from many years ago.

The product has continued to evolve under Siemens, with newer versions, integrations, APIs and capabilities added after the rebranding.

So if you used Preactor years ago, think of Opcenter APS as the current Siemens evolution of that software, not simply the old product with a new logo.

Why Do People Still Call It Preactor?

Because software names have a funny way of surviving their marketing departments.

Preactor was established in manufacturing planning and scheduling long before Siemens adopted the Opcenter branding.

Manufacturers may have:

  • Implemented Preactor years ago
  • Trained planners on Preactor
  • Built integrations around Preactor
  • Purchased consulting services for Preactor
  • Written internal procedures referring to Preactor
  • Hired employees with Preactor experience

Those habits do not instantly disappear because a vendor changes a product name.

Even in 2026, Siemens itself published partner content describing Opcenter APS as formerly Preactor APS, demonstrating that the old name remains useful when communicating with the manufacturing market.

So if someone at your factory says:

“We use Preactor.”

they may very well be referring to what Siemens now calls Opcenter APS.

Is Preactor MRP Software?

Not exactly.

The similar acronyms can make this confusing.

MRP traditionally means Material Requirements Planning.

MRP primarily helps determine questions such as:

  • What materials are required?
  • How much material is needed?
  • When will those materials be needed?
  • What needs to be purchased or produced?

APS tackles a different but related problem:

Given our demand and our actual production constraints, when can we realistically make everything?

One useful distinction is:

MRP calculates requirements.

APS creates a feasible production plan and schedule.

They often work together.

APS systems can receive demand, BOM, inventory and production-order information from ERP or MRP systems and use it to build a more realistic schedule.

Does APS Replace ERP?

Generally, no.

ERP and APS have different jobs.

ERP may manage:

  • Customer orders
  • Purchasing
  • Inventory
  • Finance
  • Costing
  • Master data
  • Material requirements
  • Business planning

APS focuses much more deeply on production planning and scheduling.

A typical relationship might look like this:

ERP:
“We need to manufacture these orders.”

APS:
“Given our machines, people, materials, setup times and current workload, here is when we can actually make them.”

APS can then send relevant planning and scheduling information back to the surrounding manufacturing systems.

Neo Digital Industries describes APS as a planning decision layer that works with ERP rather than replacing it.

Is Preactor MES Software?

Not primarily.

MES — Manufacturing Execution System — focuses heavily on what is happening during actual production.

MES may track:

  • Work-in-process
  • Operator activity
  • Material consumption
  • Production quantities
  • Scrap
  • Traceability
  • Manufacturing instructions
  • Shop-floor execution

APS focuses on deciding what should happen and when.

A simplified distinction is:

APS creates and adjusts the production schedule.

MES helps execute and record what happens on the shop floor.

The two systems can be integrated.

ATS Global specifically describes Opcenter APS integrations with ERP, Excel and MES data sources.

Is Preactor Part of MOM?

Yes — in Siemens’ portfolio structure, Opcenter APS sits within the broader Manufacturing Operations Management, or MOM, environment.

This is another reason the Preactor-to-Opcenter name change can initially be confusing.

MOM is broader than scheduling alone.

Manufacturing Operations Management can include capabilities such as:

  • Manufacturing execution
  • Production scheduling
  • Quality
  • Manufacturing intelligence
  • Traceability
  • Operations management
  • Other production-related functions

When Siemens adopted the Opcenter brand, APS became one part of that larger manufacturing operations portfolio.

Neo Digital Industries describes Opcenter APS as part of the Opcenter MOM portfolio alongside execution, quality and other manufacturing operations products.

So:

Preactor / Opcenter APS = APS software

while:

Opcenter = Siemens’ broader manufacturing operations portfolio

That distinction is worth remembering.

Where Does Preactor Fit With MOM, MES and ERP?

Here is the simplest way to picture it:

ERP

Handles much of the business requirement.

What do we need to make?

APS / Preactor / Opcenter APS

Creates a feasible production plan and schedule.

When and where can we realistically make it?

MES

Executes and records production.

What is actually happening while we make it?

MOM

The broader manufacturing operations environment connecting and managing many of those activities.

How are manufacturing operations being coordinated overall?

The boundaries can overlap, particularly because modern manufacturing suites combine multiple applications.

But those questions provide a useful starting point.

What Problems Does Opcenter APS Solve?

APS becomes particularly useful when production scheduling becomes too complicated to manage reliably through simple tools.

Potential warning signs include:

  • Production scheduling depends heavily on spreadsheets
  • Planners spend hours manually rebuilding schedules
  • Rush orders constantly disrupt production
  • Delivery-date promises are unreliable
  • Bottlenecks are difficult to predict
  • Machines are overloaded while others sit idle
  • Setup and changeover times cause scheduling problems
  • Production has many competing priorities
  • Material constraints frequently change the schedule
  • Sales and production disagree about achievable delivery dates
  • Schedules become obsolete almost immediately after they are published

Opcenter APS is intended to create schedules that account for actual production constraints and to help planners quickly model changes when reality interferes with the original plan.

Can Opcenter APS Handle Schedule Changes?

This is one of the fundamental reasons APS exists.

Factories rarely follow the original production plan perfectly.

Imagine that tomorrow morning:

  • A machine breaks.
  • A high-priority order arrives.
  • Material is delayed.
  • A customer moves a due date.
  • An operator becomes unavailable.
  • An operation takes twice as long as expected.

An APS system should help planners understand how that change affects everything else.

Modern Opcenter APS provides capabilities for scenario simulation, finite-capacity scheduling and schedule adjustment so planners can examine the effect of changing constraints and priorities.

That ability to respond to disruption is at least as important as creating the original schedule.

Does Opcenter APS Replace Excel Scheduling?

It can replace or greatly reduce dependence on spreadsheet-based production scheduling, although many manufacturers may continue to use Excel for other purposes.

Excel is extraordinarily flexible.

That is both its strength and its weakness.

A skilled planner can build a remarkable scheduling spreadsheet.

But eventually the spreadsheet may need to account for:

  • Hundreds of orders
  • Multiple machines
  • Labor calendars
  • Setup rules
  • Material constraints
  • Operation precedence
  • Alternative resources
  • Maintenance
  • Customer priorities
  • Changing due dates

At some point, maintaining the logic manually becomes difficult.

APS software is designed specifically for those scheduling problems.

Who Uses APS Software?

APS can be useful across many types of manufacturing, including environments with:

  • Complex production routings
  • High product variety
  • Constrained machines
  • Sequence-dependent setup times
  • Make-to-order production
  • Difficult bottlenecks
  • Shared manufacturing resources
  • Frequent schedule changes
  • Multiple competing orders
  • Tight customer delivery commitments

Manufacturers do not necessarily need to be enormous to benefit from advanced scheduling.

The determining factor is often production complexity, not company size.

A 60-person manufacturer can have a more difficult scheduling problem than a much larger company producing a small number of highly repetitive products.

Is Preactor Still Supported?

The old Preactor branding has largely been replaced by Siemens Opcenter APS.

Manufacturers looking for current product information, implementation services or new versions should therefore search for Siemens Opcenter APS, not just Preactor.

However, existing Preactor terminology continues to appear across Siemens partner sites, historic documentation, manufacturing discussions and installed environments.

If you are supporting an older implementation, the precise product version matters.

Do not assume that documentation for current Opcenter APS exactly matches an older Preactor installation.

What Should You Search for Today?

If you are researching a new APS implementation, use:

Siemens Opcenter APS

If you are researching older installations, migration information, consultants or historic documentation, you may also need:

Preactor APS

and:

SIMATIC IT Preactor APS

Using all three names can help when researching older manufacturing environments.

Preactor Glossary Summary

Preactor was a popular Advanced Planning and Scheduling software product acquired by Siemens in 2013.

It is now known as Siemens Opcenter APS.

Its purpose is to help manufacturers create realistic production plans and schedules while considering finite resources and real factory constraints.

In simple terms:

MRP asks what materials are required.

ERP manages much of the business requirement.

APS determines when production can realistically happen.

MES helps execute and record production.

MOM provides the broader manufacturing operations environment.

So if you searched for Preactor and ended up looking at Opcenter APS:

You are in the right place.