A human-machine interface (HMI) is the hardware or software through which an operator sees the state of a machine or process and acts on it: reading values and alarms, changing setpoints and parameters. It can be a terminal mounted in a panel door, HMI software on an industrial PC, or screens served to a web browser. The choice depends on the number of screens, controllers and operator positions, the history to keep, remote access, and where the device is installed.
What an HMI does, and where SCADA starts
NIST SP 800-82r3 defines an HMI as the hardware or software through which an operator interacts with a controller. It ranges from a physical control panel with buttons and indicator lights to an industrial PC with a colour graphics display running dedicated HMI software. The same guide says operators and engineers use HMIs to monitor and configure setpoints, control algorithms and parameters in the controller, and to see process status and history. The algorithms run in the controller; the HMI reads and writes its data.
Wikipedia's SCADA article calls the HMI the operator window of the supervisory system and one of the main elements of SCADA: part of the supervisory computer in a small system, several HMIs on client machines in a larger one. A single panel on one machine is an HMI without SCADA. What SCADA adds (data from many controllers, central alarms, history, reports) is covered in What is SCADA.
Three kinds of HMI
Operator panel (graphic terminal)
Rockwell Automation describes its graphic terminals as fully packaged devices (hardware, software and communications) tested for HMI operation, with the runtime licence included. Its selection guide VIEW-SG002D (February 2025) shows three current families:
- PanelView Plus 7, designed in FactoryTalk View Studio ME. The Standard family is limited to 1 controller, 100 screens and 500 alarms; the Performance family has no limit on these. Series B Performance terminals run a Windows 10 IoT operating system; Series A came with Windows CE. Third-party devices are reached through KEPServer.
- PanelView 5000 (5310 and 5510), designed in Studio 5000 View Designer, which is included with Studio 5000. It shares tags and Logix alarms with the controller. The 5310 handles 1 controller and 100 screens, the 5510 up to 4 controllers and 500 screens. The guide lists no support for third-party controllers.
- OptixPanel (2800C Compact and 2800S Standard), which runs FactoryTalk Optix with the runtime licence included: 8 feature tokens on the Compact and 11 on the Standard, both upgradable. The guide lists no fixed limit on displays, controllers, tags or alarms, and adds OPC UA, MQTT, C# scripting and HTML5 web clients.
The design tools behind these terminals are compared in FactoryTalk View SE vs ME vs Optix.
HMI software on a PC
The HMI runs on an industrial PC or workstation, alone or as one station of a larger system. FactoryTalk View ME runs on industrial computers once its licence is activated. FactoryTalk View SE scales from a standalone HMI to a distributed system with several servers and users.
Ignition Vision clients connect to a central gateway. Inductive Automation describes them as Java applications with no individual client install, opened through the Vision Client Launcher (Windows, Linux, macOS) in a window or full screen. Ignition is licensed per server and by module, with unlimited clients, tags and projects.
AVEVA InTouch HMI applications are built in WindowMaker; AVEVA lists OPC UA, OPC DA, SQL and .NET among its connectivity options.
A PC has room for more screens, scripts, trends and drivers, and brings an operating system to patch and a disk to back up.
Web and thin-client HMI
In this model the screens run on a server and the operator's device only displays them.
- Web clients. Ignition Perspective uses HTML5 and CSS3 for its interface, runs in a browser or a native iOS or Android app, and adapts to the screen size; Perspective Workstation runs sessions as a desktop program, including a kiosk mode. FactoryTalk ViewPoint adds HTML5 browser access to FactoryTalk View SE and PanelView Plus 7, with no client software to install. FactoryTalk Optix has native web clients. The InTouch HMI web client needs no client installation and can be read-only or read-write; InTouch Access Anywhere, on Windows Server, gives browser access to the whole application including scripts.
- Thin clients. With ThinManager, applications run and are maintained centrally and the floor devices display them; Rockwell's ASEM 6300T thin clients can boot into ThinManager with no SSD on board. Rockwell presents this as reducing the attack surface of many PCs storing applications locally.
A web or thin-client HMI saves updating software on each device, but every screen depends on the network and on the server.
What decides the choice
| Question | What to look up |
|---|---|
| How many screens, controllers and alarms? | Terminal limits: PanelView Plus 7 Standard 1 controller, 100 screens, 500 alarms; PanelView 5310 1 controller, 100 screens; PanelView 5510 4 controllers, 500 screens; OptixPanel sized by feature tokens |
| Controllers from other vendors? | PanelView Plus 7 through KEPServer; PanelView 5000 Logix only; Optix has built-in third-party drivers; Ignition has driver modules for Allen-Bradley, Siemens, Modbus, Mitsubishi, Omron and others; AVEVA InTouch HMI connects through standard interfaces such as OPC UA and OPC DA |
| How many operator positions, and who else needs to look? | One panel per machine, or a server with clients; how the product counts clients |
| Alarm and trend history | Data logging built into the terminal, or a historian |
| Recipes | PanelView 5000 recipes are controller-based; the selection guide lists recipe management for the other Rockwell families |
| Remote and web access | Web clients, VNC, remote access tools, and who may write from outside the control room |
| Environment | Rating once mounted, operating temperature, washdown, hazardous-area marking |
| Lifecycle | Status of the exact catalog number on the vendor's website |
The environment needs a closer look, because a panel lives on the plant floor:
- The PanelView Plus 7 Performance user manual describes the terminal as open-type equipment. Its NEMA, UL Type and IEC ratings apply only when it is mounted in a panel or enclosure with an equivalent rating.
- When marked on the nameplate, these terminals are suitable for Class I Division 2 Groups A to D and Class I Zone 2 Group IIC hazardous locations; the ArmorView Plus 7 variant is not certified for them. Check the nameplate of the actual unit.
- Operating temperature can differ within one family: 0 to 50 °C for the PanelView 5310, 0 to 55 °C for PanelView 5510 terminals from 7 to 15 inches, and 0 to 50 °C for the 19-inch model.
- Rockwell lists stainless-steel IP69K versions of OptixPanel Standard (10.1 to 21.5 inches), and 6181X thin clients and PCs for −20 to +70 °C with Class I Division 2, ATEX and IECEx certifications.
As a starting point: a panel suits one machine operated at the machine within the terminal's limits; several operator positions sharing alarms and history point to a server with clients; users outside the control room point to web or thin clients.
Screen design and access
Display hierarchy, use of colour and the plant style guide are covered in ISA-101 HMI design, and alarm priorities and rationalization in ISA-18.2 alarm management.
NIST notes that an operator may need the HMI immediately in an emergency and that entering credentials can delay the response. Where authentication is not supported or is judged unsuitable, NIST recommends compensating measures such as physical access control to the control room. Zones and conduits for HMI and SCADA networks are explained in the IEC 62443 article.
Replacing an old panel: a checklist
- Check the lifecycle status. Look up the catalog number from the nameplate on the vendor's website and follow the listed replacement to an active part. On 2 November 2026, Rockwell's page for the PanelView Plus 6 1000 terminal 2711P-T10C4A8 (AC input) showed it discontinued on 30 December 2021, with 2711P-T10C22A9P as the engineering replacement. That PanelView Plus 7 terminal had itself been discontinued on 30 November 2021. Its own listed replacement, 2711P-T10C22D9P, is a 24 V DC PanelView Plus 7 Performance terminal shown as active. Along the chain, the supply changed from AC to 24 V DC.
- Recover the application. Collect the design and runtime files and record the software version. Applications from PanelView Standard and Enhanced terminals and from PanelBuilder32 can be imported into FactoryTalk View Studio ME with the Machine Edition Import Wizard.
- Check communications. PanelView Plus 7 terminals use Ethernet only. Rockwell states that PanelView Standard and Enhanced applications set to serial communication must be changed to Ethernet, and points to partner gateways for other protocols.
- Check screen resolution. An application that is not resized runs in the top-left corner of the larger PanelView Plus 7 screen. Resizing means adjusting each screen's layout, especially for a widescreen terminal.
- Check the panel cut-out. Rockwell's adapter kits fit a PanelView Plus 7 Performance terminal into the cut-out of some older PanelView terminals. Rockwell warns against installing a PanelView Plus 7 Standard terminal with these kits, because the bezel can be damaged and the seal weakened.
- List the features in use (alarms, recipes, data logs, scripts, web access, third-party drivers) and check each against the target family.
- Test before the shutdown against the running controller where possible, and archive both applications.
TDL's PanelView Plus HMI migration page describes this work, including adapter kits and moving DH+, DH-485 or ControlNet links to EtherNet/IP. Other platforms are covered in Legacy HMI/SCADA migration paths, and TDL's work on FactoryTalk View, FactoryTalk Optix, AVEVA InTouch HMI and Ignition is on the SCADA and historian page. Operator stations of a process control system are discussed in What is a DCS.
Frequently asked questions
What is the difference between an HMI and SCADA?
The HMI is the operator's window onto the process. SCADA collects data from many controllers and adds central alarms, history and reports, with the HMI as one of its main elements. A panel on a single machine is an HMI without SCADA.
When is an operator panel enough?
When one machine is operated at the machine and the application fits within the terminal's limits. A PanelView Plus 7 Standard terminal, for example, is limited to 1 controller, 100 screens and 500 alarms, while the Performance family has no limit on these. Several operator positions sharing alarms and history point to a server with clients.
Can operators use a web browser as the HMI?
Yes, on platforms built for it: Ignition Perspective, FactoryTalk ViewPoint for FactoryTalk View SE and PanelView Plus 7, FactoryTalk Optix web clients and the AVEVA InTouch HMI web client. The screens then depend on the network and the server, and write access from outside the control room has to be decided.
Can a PanelView Plus 7 be installed in a hazardous area?
Rockwell's user manual states that PanelView Plus 7 Performance terminals marked for it are suitable for Class I Division 2 and Class I Zone 2 hazardous locations; the ArmorView Plus 7 variant is not certified for them. The nameplate of the actual unit decides.
How do I know whether my HMI model is still sold?
Look up the catalog number on the vendor's website and follow the listed replacement until you reach an active part. The listed replacement can itself be discontinued and can change details such as the supply voltage, as the PanelView Plus 6 example above shows.
Sources
- Rockwell Automation, VIEW-SG002D-EN-P, Visualization Solutions Selection Guide, 02/2025 — pp. 2–11, 13–21
- Rockwell Automation, 2711P-UM008K-EN-P, PanelView Plus 7 Performance Terminals User Manual, 04/2024 — pp. 21–22
- Rockwell Automation, 2711P-AP005F-EN-P, Legacy PanelView Terminals to PanelView Plus 7 Terminals Catalog Number Conversions Migration Guide, 07/2022 — pp. 2, 34–35
- Rockwell Automation, 2711P-T10C4A8 product page, lifecycle status read 2 November 2026
- Rockwell Automation, 2711P-T10C22A9P product page, lifecycle status read 2 November 2026
- Rockwell Automation, 2711P-T10C22D9P product page, lifecycle status read 2 November 2026
- Rockwell Automation, Runtime entitlements and feature tokens for target devices, FactoryTalk Optix Solutions Application Technique
- Inductive Automation, Perspective, Ignition 8.3
- Inductive Automation, Perspective Module, Ignition 8.3
- Inductive Automation, Vision Module, Ignition 8.3
- Inductive Automation, Launchers and Workstation, Ignition 8.3
- Inductive Automation, Licensing and Activation, Ignition 8.3
- Inductive Automation, Driver Modules, Ignition 8.3
- AVEVA, AVEVA InTouch HMI
- AVEVA, AVEVA InTouch HMI datasheet, 12/2023
- NIST, SP 800-82r3, Guide to Operational Technology (OT) Security, 09/2023 — pp. 10, 97, 163
- Wikipedia, SCADA
Read 2 November 2026. This article paraphrases the sources and does not quote them; read the original documents before designing or working on a system.