HMI panels and PLC controllers
An operator panel and a controller are the two components that decide whether a machine is comfortable to work with. The controller determines what the machine is capable of; the panel determines whether the operator can use those capabilities without calling a technician. Automation Dariusz Kulik is an automation integrator based in Poland, with fifteen years of practice in PLC and HMI work, delivering projects throughout the country. The scope covers controller and panel programming, hardware selection, integration of individual machines with plant systems, and screen design that a shift operator can read at a glance.
Work of this kind rarely starts from a blank sheet. More often there is a working machine with an obsolete panel, a controller whose original programmer is no longer available, or a production cell that has to start reporting its data to a higher-level system. Each of these situations has a different least-invasive solution, and identifying it is the first part of the job. Further background is set out in where to start with production automation.
Panel replacement without interfering with the controller
A failed operator panel does not imply a failed control system. Where the controller program is sound and the machine performs correctly, the rational course is to replace the panel alone and leave the controller untouched. The visualisation is rebuilt on the new hardware, the communication protocol is retained, and the controller program is not recompiled — which means the validated machine behaviour is not put at risk. This is how the CIP station retrofit in a dairy was carried out: a damaged Siemens panel was replaced with an Xinje TG unit, the visualisation was rebuilt to be functionally identical, the existing S7 controller was left in place and PROFINET communication was retained. The cost saving against a full control system replacement was around 70%, and the work was completed in under a week.
One technical detail decides whether such a substitution is feasible at all. Siemens S7-1200 and S7-1500 controllers require PUT/GET communication to be enabled and the relevant data blocks to be non-optimised before a third-party panel can address them. Where access to the controller project is unavailable, this cannot be arranged and the assessment has to be made before any commitment is given. The criteria for choosing replacement hardware are discussed in how to choose an operator panel.
Integration with plant systems
Machines are increasingly expected to report rather than merely operate. Integration is implemented over Modbus RTU and Modbus TCP, PROFINET and EtherNet/IP, according to what the existing infrastructure already speaks. The practical work consists of establishing an address map, defining which variables leave the machine and at what rate, and confirming that the added communication load does not disturb the control cycle. The relationship between machine-level data and higher-level production management is outlined in the article on SCADA and MES systems.
Safety functions and the limits of a touchscreen
Safety functions are implemented by a safety relay or a safety controller, including over industrial networks using PROFIsafe, CIP Safety or FSoE. A hardwired circuit is not the only admissible option. What a touchscreen can never do is serve as an emergency stop: EN ISO 13850 requires a manually actuated device with latching and direct opening action, and no graphical control satisfies that requirement. An emergency stop button therefore remains physical, whatever else moves onto the screen.
A second boundary concerns the working environment. In an explosive atmosphere a standard operator panel is inadmissible regardless of its IP rating; the ingress protection class addresses dust and water, not ignition risk, and the two are frequently confused during specification.
Hardware selection
Selection follows from the interfaces the machine already has and the operating conditions in the hall. For reference, the Xinje TS series comprises the TS5-700-E (7 in, 800×480) and the TS5-1000-E (10.1 in, 1024×600), both built on a Cortex-A7 running at 1 GHz with 128 MB of memory, resistive touch, IP65 protection at the front and a 24 V DC supply. Connectivity comprises COM1 (RS232/485), COM2 (RS232/485/422) and an RJ45 Ethernet 10/100 port with Modbus TCP; the panels are configured in TouchWin Pro. Controller selection follows the same logic and is examined in the PLC selection guide.
Component selection and supply
Alongside engineering services, we select and supply automation components: PLC controllers, operator panels, servo drives and inverters — including the Xinje equipment on which most of the deployments described here are based. Selection follows the process requirements and the communication protocols of the existing equipment, not the catalogue.
Supply can be combined with commissioning: the component arrives at the plant configured, with the program or screen project prepared. This shortens downtime when a single device is replaced — the customer receives an element ready for installation.
Scope of work
- PLC programming and modification of existing controller programs
- Operator panel programming and design of readable screens, alarm lists and diagnostic views
- Selection of controllers, panels and communication modules to suit the existing installation
- Panel replacement with the controller left untouched, including rebuilding the visualisation
- Integration over Modbus RTU/TCP, PROFINET and EtherNet/IP
- Implementation of safety functions using a safety relay or safety controller
- Commissioning, operator training and handover documentation
Indicative budget and lead time
Indicative bands are as follows: a single machine retrofit PLN 30,000–50,000 (approx. EUR 7,000–12,000); a semi-automatic machine PLN 50,000–150,000 (approx. EUR 12,000–35,000); a robotic workstation PLN 150,000–500,000 (approx. EUR 35,000–115,000); a production line retrofit PLN 80,000–400,000 (approx. EUR 19,000–95,000). Return on investment typically falls between 12 and 36 months, and between 12 and 24 months for a well-chosen first project. Lead times from contract to handover are 1–3, 2–4 or 3–6 months depending on scale. The cost structure is broken down in how much production line automation costs.
Example from our projects
The semi-automatic machine for assembling shaver heads combines an Xinje TG panel with an Xinje DS2 servo drive holding accuracy to tenths of a millimetre. Throughput rose threefold and defects fell to zero, but the decisive design choice was placing the machine settings on the panel: changing them no longer requires a programmer. The CIP station retrofit in a dairy illustrates the opposite priority — the least possible interference, at around 70% of the cost of a full replacement.
Frequently asked questions
Can a panel be replaced without altering the controller program?
In most cases yes, provided the controller exposes its data to an external device. With Siemens S7-1200 and S7-1500 this means enabling PUT/GET communication and using non-optimised data blocks, which requires access to the controller project. Where that access exists, the visualisation is rebuilt on the new panel and the controller program remains unchanged, as at the CIP station.
Does an emergency stop have to be a physical button?
Yes. EN ISO 13850 requires a manually actuated device with latching and direct opening action, and a touchscreen cannot satisfy either condition. The remaining safety functions may be implemented by a safety relay or a safety controller, including over PROFIsafe, CIP Safety or FSoE — a hardwired circuit is not the only route.
Does modernising a machine require a fresh conformity assessment?
It depends on whether the change constitutes a substantial modification, and the test is a change in risk — not an increase in throughput or speed. Regulation (EU) 2023/1230 applies from 20 January 2027 and replaces Directive 2006/42/EC. A notified body is involved only for high-risk categories. The choice between modernisation and replacement is examined in machine retrofit or new machine.
Is a panel with a high IP rating sufficient in a hazardous area?
No. In an explosive atmosphere a standard operator panel is inadmissible regardless of its IP rating. Ingress protection describes resistance to dust and water and says nothing about ignition risk, so the two must not be treated as interchangeable during specification.
Request a quote
Tell us what the machine does and what is not working — a failed panel, a controller nobody can modify, or a machine that has to start sharing its data. We will arrange a site visit, and you will have a quote within 48 hours of it. Call +48 796 019 414 or write to biuro@automation.net.pl. We deliver projects throughout Poland. You can also send your enquiry via the contact form.