PLC Programmer for Siemens TIA Portal: S7-1500 and S7-1200
Outsourced PLC programming for new plants, expansions and migrations — with meaningful symbolic names and a clear block structure, so your maintenance team can read the program themselves when a fault occurs.
- each language where it plays to its strengths
- FBD/LAD + SCL
- proven basic functions, across projects
- 1 library
- FDS & operating manual at handover
- Docs
In short
In TIA Portal, we program Siemens S7-1500 and S7-1200 controllers, including fail-safe F-CPUs with ProfiSafe — for new plants, extensions to existing projects and migrations from STEP 7 Classic or CODESYS. Behind this is Prybisch Automation, the engineering practice of freelance PLC programmer David Prybisch, based in Luxembourg. Sequence and interlock logic is written in FBD or LAD so your maintenance team can follow it in online status; we use SCL for calculations, data handling and library blocks. Engineering is done remotely and commissioning on site, across Germany, Austria, Switzerland, Luxembourg and France. Every block is tested before commissioning.
Outsourcing PLC programming: how we work with your team
Whether you hand over a complete control program or need extra capacity in your own team, your contact is the person who programs, tests and commissions. Nothing gets lost between desks, and questions are answered where the program is written.
- Starting point: specification or functional description. An existing specification is checked against the I/O list and circuit diagrams, and open points are settled before the first block is written. If there is none, a functional design specification (FDS) is drawn up in German or English and agreed with everyone involved.
- Programming standard: block structure by plant area, basic functions from a proven block library, symbolic names, network titles and comments throughout. If your site has its own programming standard, that standard applies.
- Remote or on site: programming and system testing are done remotely in the test setup, commissioning at your plant. Short-notice site visits are routine in the Saar-Lor-Lux region; beyond it, assignments are scheduled in advance.
- Panel building and commissioning: coordination with the panel builder via I/O lists and drawings, a system test before delivery, commissioning together with your installation team or independently.
- Handover: a program with complete symbolic names, network titles and comments, the FDS in its final state, an operating manual and a briefing for your maintenance staff. Later changes can be made by your own team.
The program as the source of truth
For existing plants the work begins in the legacy program: what runs in the controller is the plant's reality — not what is on the plan. Even hard cases are everyday practice, such as reconstructing symbolic names and program structure from an online extract with no source project, comments or documentation.
Rebuild instead of a 1:1 carry-over
A program that has been changed by changing hands for 15 years deserves more than a migration wizard when it moves over:
- Dead blocks, duplicate flags and hard-coded values are cleaned up rather than preserved.
- Structured data types, symbolic addressing and the integrated diagnostics of the S7-1500/S7-1200 are genuinely put to use.
- The proven plant logic is preserved — what is new is the structure beneath it.
Programming standard: readable for maintenance
A PLC program is written once and then read by others for years — usually during a fault, under time pressure, in online status. So there is no language dogma, but a clear division of labour: each language is used where it plays to its strengths. Throughout, every network has a title, every operand a meaningful symbolic name, and anything that does not explain itself a comment. The result reads as documented and behaves like the plant.
- FBD and LAD for sequence and interlock logic: enables, interlocks and step conditions can be followed signal by signal in online status — the network shows directly which condition is missing.
- SCL for calculations, data handling and library blocks: blocks with a clear interface, called in the network like any other block.
- Standard block library: motors, valves, interlocks and fault messages are built from proven library blocks — uniformly structured, uniformly diagnosable, operated the same way in every project.
- A structure that follows the plant: the project tree mirrors the plant areas, not the history of the program — anyone looking for a damper finds it under dampers.
- For migrations from S5, STEP 7 Classic or CODESYS, FBD/LAD is the standard, so the carried-over plant logic becomes readable for your maintenance team.
Fieldbus and the sensor/actuator level in the program
A program does not end at the CPU terminal. PROFINET distributed I/O and legacy PROFIBUS DP segments enter the project as a process image, AS-Interface segments via a CM AS-i master in an ET 200SP or via a gateway, IO-Link masters including device parameters in TIA Portal. What counts is what the program makes of it: station failure, duplicate address and ground fault are evaluated and reported as a clear message instead of ending as a silent loss of signal in the sequence logic.
- PROFINET / PROFIBUS DP: distributed I/O in the process image, diagnostics down to the channel.
- AS-Interface (AS-i): master in an ET 200SP or a gateway, slave addressing and diagnostics in the program.
- IO-Link: master configuration and device parameters in TIA Portal.
Platforms and versions
New programs are developed in TIA Portal for the current generation of Siemens controllers. Existing projects are continued in the version they run on at your site — a version upgrade only happens once agreed with you.
- Controllers: S7-1500 and S7-1200, distributed I/O via PROFINET, for example ET 200SP.
- Safety: fail-safe F-CPUs of the S7-1500 and S7-1200 families with ProfiSafe I/O, safety functions to ISO 13849.
- Software: TIA Portal V13 to V21, with the HMI in WinCC Unified from the same source.
- Migration to TIA Portal: S5 and S7-300/400 from STEP 7 Classic are covered by the separate control system retrofit service, WAGO, CODESYS and Beckhoff TwinCAT controllers by the CODESYS to TIA Portal migration.
Tested before it goes to the plant
Every basic function and every sequence is checked in a dry run against defined scenarios — normal operation, fault cases, limit values — and in simulation where it makes sense. For the complete system, the end-to-end test follows in the test setup on real target hardware. At the plant, the job is commissioning, not programming.
Related services
- Retrofit S5/S7 → TIA PortalMigrate S5, S7-300 or S7-400 to TIA Portal on S7-1500/S7-1200 — often without rebuilding the control cabinet.
- Commissioning & End-to-End TestThe complete system tested beforehand — on the hardware that will later work at the plant.
- Retrofit CODESYS → TIA PortalMigrate WAGO 750/PFC and Beckhoff TwinCAT to TIA Portal on an S7-1500 with WinCC Unified — from legacy code that has been read and understood to a documented Siemens solution.
Frequently Asked Questions
Who programs Siemens PLCs in TIA Portal as a freelance service provider?
Prybisch Automation, David Prybisch's engineering practice based in Luxembourg, working in Germany, Austria, Switzerland, Luxembourg and France. The scope runs from the functional description and the PLC program for S7-1500 and S7-1200, including fail-safe CPUs, to system testing, on-site commissioning and handover with documentation. Programs are written with consistent symbolic names and a clear block structure, so your maintenance team can read them.
Do you also take on existing TIA projects written by other programmers?
Yes — extensions, troubleshooting and clean-up work in existing TIA projects are part of everyday business, including as cover when your team is short of capacity. Before larger interventions, a program analysis provides clarity on structure, legacy issues and risks. An existing programming standard is adopted rather than adding a second style to the project.
Which language do you program in — FBD, LAD or SCL?
All three, each where it plays to its strengths. Sequence and interlock logic is written in FBD or LAD because your maintenance team can follow it signal by signal in online status; we use SCL for calculations, data handling and library blocks. For migrations from S5, STEP 7 Classic or CODESYS, FBD/LAD is the standard, so the carried-over plant logic becomes readable.
What exactly does the block library give me?
Uniform basic functions mean: the same diagnostics, the same operating behavior and the same documentation in every project. Your maintenance team does not have to learn individual handwriting — and expansions build on what is proven.
Do you also program S5 and STEP 7 Classic?
We read, analyze and migrate legacy programs from the S5 and STEP 7 Classic worlds — new developments are built in the TIA Portal. For legacy plants the goal is usually migration to the S7-1500/S7-1200 rather than maintaining phased-out systems.
Discuss your PLC project
New plant, expansion or migration — briefly describe your project and you get an honest assessment of the effort and approach.
✓ Non-binding initial consultation✓ Response time < 24h on business days