Upgrading the HMI for Modular Production System: Smarter Control and Station Independence
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As part of the continuing development of my Modular Production System (MPS) digital twin, I’ve focused on significantly improving the Human-Machine Interface (HMI) to support better visualization, control, and flexibility for each of the four key stations: Distribution, Pick and Place, Sorting, and Dismantle.
Unified HMI Template with Dynamic Navigation
Unified HMI Template with Dynamic Navigation
To streamline the experience, a unified HMI screen template was developed and applied across all four stations. A drop-down menu has been implemented at the top of the screen, enabling users to switch between station views easily. This was achieved by creating a list of station names and assigning them numerical values that correspond to internal logic for screen switching. This approach ensures consistent navigation and simplifies the HMI logic's structure.
A dedicated HMI Function Block (FB) was also created within the TIA Portal to handle all variables related to the HMI. This includes screen selection, button states, indicators, and control logic. Centralising these variables helps keep the system modular and makes future expansion or refactoring more manageable.
HMI Template
HMI Template
List for HMI Screens
List for HMI Screens
Reset Buttons and Individual Station Control
Reset Buttons and Individual Station Control
Each station’s screen now includes a Reset button, which sets the internal sequence controller back to Step := 0;. This is extremely helpful for:
Recovering from simulation errors.
Restarting specific operations during debugging.
Allowing independent operation of stations during testing phases.
These reset buttons are connected to the PLC and work in conjunction with the logic in each station’s function block, ensuring that the state machine is properly re-initialized.
Optimising Responsiveness: Tag Refresh Rate Adjustment
Optimising Responsiveness: Tag Refresh Rate Adjustment
Another crucial improvement was reducing the refresh rate of HMI tags from the default 1 second to 100 milliseconds. This change allows:
Near-instant updates to indicators and sensor feedback.
Real-time responsiveness to user inputs such as button presses or toggles.
A smoother and more realistic simulation experience, especially when working in Siemens NX alongside PLCSIM Advanced.
Distribution and Pick and Place Stations
Distribution and Pick and Place Stations
Both of these stations are currently automated and require no user control. Their respective HMI views focus on:
Real-time sensor and actuator indicators for monitoring performance.
A Reset button for manual override or reinitialization.
This structure maintains clarity while giving essential diagnostics for debugging and demonstration purposes.
Distribution Station
Distribution Station
Pick And Place Station
Pick And Place Station
Sorting Station: Interactive Production Control
Sorting Station: Interactive Production Control
This screen provides a more interactive control panel. Users can define how many red, black, and silver workpieces should be allocated to Slide 1 and Slide 2, effectively customising the order per production run. The screen includes:
Counters to display current workpiece counts by colour.
Buttons to manually collect completed orders.
Indicators for all relevant actuators and sensors.
This allows dynamic testing of the system's sorting capabilities and supports real-time adjustments based on user input.
Dismantle Station: Recycling Control and Future-Proofing
Dismantle Station: Recycling Control and Future-Proofing
Currently under development, this station's screen features indicators for sensors and actuators, a manual "Empty Recycled Workpieces" button, and a toggle switch to enable automatic workpiece collection (linked to the Object Sink in Siemens NX MCD). While the workpiece recycling logic is functional, the lid separation sequence is pending due to unresolved issues in the Pick and Place station. Once those are resolved, this station will be upgraded to handle lids and workpieces separately. At present, the counter for recycled units is shared with the sorting station, but this will likely be decoupled in future versions for greater clarity.
Summary
Summary
The HMI system now provides a clean, functional, and expandable interface to control and monitor the entire MPS digital twin. The improvements in refresh speed, structured screen layout, dynamic control, and integration with logic blocks not only streamline testing but also mirror real-world industrial control environments.
Future Enhancements Will Include:
Complete lid dismantling logic in the Dismantle Station.
HMI alerts and error messages for fault diagnostics.
Node-RED integration for cloud-based monitoring and analytics dashboards.
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