The short answer is yes,an HMI(Human-Machine Interface)can operate without a PLC—but its capabilities depend on how it’s designed and deployed.While HMIs are traditionally paired with PLCs for industrial automation,advancements in technology now allow HMIs to function independently or with alternative controllers for specific tasks.In this article,we’ll clarify when and how HMIs can work without PLCs,explore practical use cases,and introduce Unimat HMI—a versatile,budget-friendly series(4.3”,7”,and 10.1”)with free software and sample testing to simplify your automation journey.
HMI vs.PLC:Understanding Their Roles
HMI:A touchscreen interface that lets operators monitor data,input commands,and visualize processes.
PLC:A programmable controller that executes logic to manage sensors,actuators,and machinery.
Typically,HMIs and PLCs work together:
The HMI displays data from the PLC.
The PLC processes inputs and controls outputs.
But what if you don’t have a PLC—or don’t need one?
When Can an HMI Work Without a PLC?
1.Standalone HMI with Built-In Logic
Some advanced HMIs,like Unimat’s UH Series,include embedded controllers or support scripting,enabling them to:
Perform basic logic(e.g.,timers,counters).
Directly communicate with sensors,drives,or IoT devices via protocols like Modbus RTU,MQTT,or Ethernet/IP.
Example:A standalone Unimat 7”HMI monitors temperature sensors in a greenhouse,triggers fans via relays when thresholds are exceeded,and logs data to an SD card—all without a PLC.
2.HMI as a Data Gateway
HMIs can act as intermediaries between devices and cloud/SCADA systems:
Collect data from smart sensors(e.g.,pressure,flow meters).
Transmit data to databases or dashboards via Wi-Fi/4G.
Example:A 10.1”Unimat HMI in a solar farm aggregates inverter data and sends it to a cloud platform for remote monitoring.
3.Simple Display and Logging Tasks
For non-control applications,HMIs can:
Display static information(e.g.,safety instructions,maintenance schedules).
Log operator inputs or equipment runtimes.
Limitations of PLC-Free HMIs
While standalone HMIs are versatile,they’re not ideal for:
Complex Control:Multi-axis motion,PID loops,or safety-critical processes still require a PLC.
High-Speed Operations:Most HMIs lack the real-time processing power of PLCs.
How to Set Up a Standalone HMI:Step-by-Step
1.Choose the Right HMI
Opt for models with:
Built-in I/O Ports:Connect sensors/actuators directly(e.g.,Unimat HMI’s RS485,Ethernet,USB).
Scripting Support:Use Lua,Python,or vendor-specific logic for basic automation.
2.Connect Peripheral Devices
Sensors:Wire temperature probes,level sensors,or pushbuttons to the HMI’s digital/analog inputs.
Actuators:Link relays,valves,or indicators to outputs.
3.Program the HMI
Using Unimat’s free HMI Design Software:
Create screens to display data or accept inputs.
Write scripts to trigger actions(e.g.,“IF Temp>30°C,THEN Start Fan”).
4.Test and Deploy
Simulate workflows with Unimat’s debugging tools.
Mount the HMI and monitor performance.
Unimat HMI:Affordable,Flexible,and PLC-Ready
Unimat’s HMI series offers unmatched versatility for both standalone and PLC-integrated applications.Available in 4.3”,7”,and 10.1”sizes,here’s why they’re a top choice:
1.Standalone Capabilities
Embedded Logic:Use built-in function blocks(timers,math operations)or JavaScript for basic automation.
Direct Device Integration:Connect to Modbus sensors,VFDs,or barcode scanners without a PLC.
2.Free,Powerful Software
Drag-and-Drop Design:Create custom interfaces without coding.
Pre-Built Templates:Accelerate deployment for common tasks(alarms,data logging).
Cross-Platform Compatibility:Export projects across Unimat HMI models.
3.Budget-Friendly Pricing
4.Rugged Industrial Design
IP65 Front Panel:Resists dust,water jets,and oil splashes.
Wide Temperature Range:Operates from-20°C to 60°C in harsh environments.
5.Risk-Free Testing
Free Sample Program:Test any Unimat HMI model in your facility.
Real-World Applications of Standalone HMIs
Agricultural Monitoring:A 4.3”Unimat HMI tracks soil moisture sensors and controls irrigation pumps via relays.
Retail Kiosks:A 10.1”HMI displays product catalogs and collects customer feedback without backend systems.
HVAC Control:A 7”HMI manages building temperature and fan speeds using built-in logic.
FAQ:Standalone HMI Solutions
Q:Can Unimat HMIs be integrated with PLCs later?
A:Of course.Unimat has launched a new smart all-in-one that combines HMI and PLC.
Q:What are the main disadvantages of not using a PLC?
A:Limited ability to handle complex tasks.For advanced control,pair a Unimat HMI with a PLC.
Q:How secure are standalone HMIs?
A:Unimat HMIs offer password protection,user roles,and encrypted data storage.
Why Unimat HMIs?
Dual-mode flexibility:Start with standalone and expand with PLCs later.
Global support:24/7 technical support and 3-year warranty.
Sustainability:Low-power design reduces energy costs.
While HMIs have traditionally been paired with PLCs,modern solutions such as Unimat HMIs are proving that they can operate independently to perform basic monitoring,logging,and control tasks.With free software,rugged hardware,and affordable pricing,Unimat enables businesses to deploy cost-effective automation—whether as a standalone system or part of a larger PLC network.
Ready to explore standalone HMI solutions?
Visit Unimat’s website to download free software,request samples,or consult with its automation experts.
