Many factories and workshops still use old machines that have worked reliably for years. But these "veteran" machines often have outdated control panels-bulky buttons, blurry black-and-white screens, or even just simple indicator lights. These old controls make operations complicated, slow down work, and are hard to maintain. The good news is you don't need to replace the whole machine. Retrofitting with Siemens HMI (Human-Machine Interface) touchscreens can give old equipment a new lease on life. This blog will show you how to upgrade old machines with modern Siemens HMI controls, including key steps, recommended models, and real benefits.
Why Retrofit Old Machines with Siemens HMI?
Old control systems have many problems: they are hard to operate, cannot track real-time data, and often break down because their parts are no longer made. Upgrading with Siemens HMI fixes these issues and brings more advantages:
1. Improved Usability and Efficiency
Siemens HMI touchscreens replace messy buttons with easy-to-use 65,536-color displays and fast 5ms touch response. Operators can set parameters, check real-time status, and access digital operation guides with just a few taps-even while wearing thick work gloves. This is thanks to the panels' anti-glare and pressure-sensitive touch technology. It cuts training time for new staff by up to 40% and lowers operational errors by 25%. For example, a German automotive parts factory in Bavaria upgraded its 20-year-old paint shop robots with Siemens HMI TP700 and TP1200 panels. The panels' high-contrast displays (1000:1 brightness ratio) solved visibility problems in the dusty workshop. Operators said daily work efficiency rose by 30%, as parameter adjustments that once took 5 minutes now take just 45 seconds.
2. Reliable Performance for Industrial Environments
Siemens HMI is built for harsh industrial environments. It works stably in temperatures from -20℃ to +70℃ and has an IP65 front-panel rating-meaning it is dustproof, waterproof, and resistant to oil splatters and high-pressure cleaning. Most models are shockproof (10g acceleration for 11ms) and anti-static (±2kV contact, ±8kV air). Unlike cheap touchscreens that last only 1-2 years, Siemens HMI panels have an average lifespan of 8-10 years. This matches the durability of old machines and avoids frequent replacements. For instance, a Finnish pulp mill working in sub-zero temperatures has used Siemens HMI panels for 9 years without major failures-outperforming the 3-year lifespan of the generic touchscreens it used before.
3. Easy Integration and Scalability
Siemens HMI is compatible with 90% of old PLCs (including non-Siemens brands like Allen-Bradley and Mitsubishi) and supports multiple communication protocols: PPI, Modbus RTU, Profinet, and Ethernet/IP. For machines with old RS485 ports, the panels can connect directly at a 187,500 bps baud rate. For older serial ports, you can use a Siemens protocol converter (model 6ES7 972-0AA02-0XA0). It integrates smoothly with Siemens TIA Portal V18/V19 software, supporting up to 2,000 variables and 1,000 alarm messages per project. Later, you can easily add more functions-such as USB-based historical data logging (saved as TXT/Unicode files) or remote monitoring via Teamcenter-without changing the core PLC program.
Key Siemens HMI Models for Retrofitting Old Machines
Siemens offers a variety of HMI panels suitable for retrofitting. Below are three cost-effective models that work well with old equipment:
1. Siemens KTP400 Comfort Panel
This 4.3-inch compact Siemens HMI (model 6AV2123-2MB03-0AX0) has a 480x272 pixel TFT display. It supports both resistive touch and mechanical key operation-great for operators who like tactile feedback. With a slim 45mm depth and 182x128mm installation cutout, it fits easily into small control cabinets of old machines like packaging equipment or lathes. The KTP400 supports up to 500 variables, 200 alarm messages, and direct RS485/RS232 connections. It is fully compatible with Siemens S7-300/400 PLCs and uses WinCC Flexible 2008 SP4 software for simple drag-and-drop setup. A small bakery in Austria used this model to upgrade its 1990s dough mixers, cutting parameter setup time by 60%. It's perfect for Siemens HMI touchscreen upgrade for old machines in small industries.
2. Siemens TP700 Comfort Panel
For medium-sized machines (like conveyor lines or mixers), the 7-inch TP700 Comfort Panel (6AV2124-0GC01-0AX0) is a budget-friendly choice. It has an 800x480 pixel display, 256MB internal memory, and supports up to 1,000 variables. The larger screen lets you view real-time production speed, motor load, and fault alerts side by side, with color-coded indicators (red for errors, yellow for warnings). Magna Bohemia, a Czech automotive component supplier, used this Siemens HMI to upgrade 15-year-old paint shop equipment. The panels replaced old push-button stations, allowing one-touch access to maintenance schedules and fault checks. The upgrade extended the machines' service life by 10 years and reduced unplanned downtime by 35%.
3. Siemens TP1200 Comfort Panel
If you need advanced functions for large machines like injection molding equipment or CNC lathes, the 12-inch TP1200 Comfort Panel (6AV2124-0JC01-0AX0) is ideal. It features a 1280x720 HD display, capacitive multi-touch technology, and 1GB internal memory. It supports up to 2,000 variables and 32 languages-essential for international factories. The panel can run custom scripts via WinCC, enabling complex data analysis such as production yield tracking and energy consumption reports. A German automotive parts plant in Stuttgart used this model to upgrade its 2005 injection molding machines. The Siemens HMI connected to the factory's MES system, syncing real-time data with the central control room. This low-cost Siemens HMI retrofitting solution cost 40% less than buying new machines and doubled production traceability.
Step-by-Step Siemens HMI Retrofitting Process
Retrofitting with Siemens HMI requires a clear process to avoid machine downtime. Here's a simple 4-step guide:
Step 1: Evaluate the Old Machine and Plan
First, carefully evaluate the old machine's control system: Note the PLC model (e.g., Allen-Bradley Micro800 or Mitsubishi FX series), available communication ports (RS232/RS485/Ethernet), and existing I/O points. Measure the control cabinet's internal space to confirm the Siemens HMI's installation cutout size (e.g., 182x128mm for KTP400, 292x188mm for TP700). For machines with only RS485 ports, choose a Siemens HMI with a built-in serial port or prepare a protocol converter. Set it to 187,500 bps baud rate, HMI station address 1, and PLC station address 2 to avoid conflicts. Also, plan the screen layout-copy the old button functions and add color-coded zones (green for operation, red for emergency stop) to reduce operator learning time. For example, when upgrading old lathes, assign dedicated touch areas for spindle speed (0-3000 RPM) and feed rate (0.01-5 mm/rev) based on the machine's original settings.
Step 2: Prepare Tools and Software
Gather the necessary tools and materials: Siemens HMI panel, matching mounting brackets (Siemens part number 6AV6671-8XB10-0AX0), shielded communication cables (CAT5e for Ethernet, twisted-pair for RS485), and a laptop with TIA Portal V18/V19 software. Download the latest WinCC runtime (use HMI_PIU_Installer for V18/V19 models) and install the right communication driver (e.g., SIMATIC S7 200 SMART driver for older Siemens PLCs). For non-Siemens old PLCs, prepare a protocol converter if needed. Make sure it supports two-way data transfer, so the Siemens HMI can send control commands and receive status data from the machine. Also, get a Siemens USB/PPI cable (6ES7 901-3DB30-0XA0, E-STAND version 05 or higher) to download projects to the HMI panel.
Step 3: Install and Connect the Siemens HMI
First, turn off the machine's power and lock the circuit breaker to ensure safety. Remove the old control panel and clean the mounting area. Mount the Siemens HMI with the brackets, leaving at least 5cm of space around it for ventilation (to prevent overheating in high-temperature environments). Connect the 24V DC power cable (1.5mm² wire gauge) and communication cable: for Ethernet, plug it into the PLC's Ethernet port; for RS485, wire it to terminals A/B of both the HMI and PLC. Follow this hardware installation order: install TIA Portal software and set up the project first, then update the PLC firmware to a compatible version (e.g., V4.5 for S7-300 PLCs), and finally connect the Siemens HMI. This order prevents system conflicts and ensures smooth communication between devices.
Step 4: Configure, Test, and Train
Use TIA Portal to configure the Siemens HMI: Set up touch buttons with custom icons, data displays (showing temperature, pressure, and speed with 0.1-unit precision), and fault alerts with 80dB audible alarms. Set up historical data logging to save 3 months of operation records to a USB drive (supports up to 32GB external storage). First, test the system offline with the PLC SIM Advanced simulator. Simulate common operations (start/stop, parameter adjustment) and fault scenarios (overload, low pressure) to make sure all functions work. Once tested, switch to online mode and run the machine for 24 hours to check stability, monitoring HMI response time and data transmission accuracy. Finally, train operators to use the new Siemens HMI, focusing on new functions like date/time-based data queries and one-click fault diagnosis.
Real Benefits of Siemens HMI Retrofitting
Many foreign factories have seen great results after retrofitting with Siemens HMI. Magna Bohemia's Czech paint shop upgrade not only extended the 15-year-old machines' service life by 10 years but also boosted production capacity by 35%. The HMI's real-time fault alerts cut troubleshooting time from 2 hours to 15 minutes. A U.S. food processing plant in Illinois upgraded 30 old filling machines with Siemens HMI KTP400 panels. The panels' precise parameter control (±0.1ml filling accuracy) improved product consistency. Remote monitoring via TIA Portal let managers track production from the office, reducing fault downtime by 40% and cutting annual maintenance costs by $20,000. Additionally, a German pulp mill used Siemens HMI TP1200 panels to upgrade 2003-vintage conveyor systems, which enabled energy consumption tracking and reduced electricity costs by 12%.
For small businesses, Siemens HMI retrofitting is more cost-effective than buying new machines. You can recover the investment in 6-12 months through higher efficiency and lower maintenance costs.
Useful Tips for a Successful Siemens HMI Upgrade
- Hire Qualified Personnel: The upgrade involves 24V DC electrical wiring and software setup (protocol configuration, screen design). If you lack experience, hire Siemens-certified technicians or contact Siemens field service. They can provide on-site support for complex integrations, such as connecting Siemens HMI to old non-Siemens PLCs.
- Backup Old Settings: Save the old PLC program before upgrading. This lets you switch back to the old system if there are problems with the Siemens HMI.
- Test Offline First: Do not test on the production line. Use TIA Portal's offline simulation function or a physical test bench with the same PLC model. Test all functions-including emergency stops, fault alerts, and data logging-for at least 8 hours.
- Maintain the System: Regularly update the Siemens HMI firmware and clean the touchscreen to keep it running well.
Final Thoughts
Retrofitting old machines with Siemens HMI is a smart way to modernize your factory without overspending. It makes machines easier to use, extends their life, and lays the groundwork for smart factory management. Whether you're upgrading small equipment or large production lines, Siemens HMI provides reliable, easy-to-use solutions. Follow the steps above, choose the right model, and your old machines will work like new!
If you're ready to start your Siemens HMI retrofit, focus on Siemens HMI installation steps for old machinery and use Siemens HMI WinCC for machine retrofitting to get the best results.
