Free HMI and SCADA builder, in the browser

Draw an operator screen and run it against real ladder logic, with no account, no download and no tag limit. The runtime is the same scan engine the PLC simulator uses, so a start button on the glass starts the motor in the program.

The tag limit, which is usually the catch

Most free SCADA is free up to a number of tags, and the number is chosen carefully: high enough to build a demonstration, low enough that a real machine needs the paid tier. You find out at the point where the screen is nearly finished.

There is no tag count here, because nothing is being licensed. What an account adds is a project to file the application against, so the screens sit with the program, the drawings and the documents, and screen generation from a description, which needs a model and therefore a key that belongs to somebody.

What it will not do

• It does not talk to plant equipment. The runtime is the simulator, which is what makes a screen testable at a desk.
• It does not deploy to a panel. There is no download to a TP1500 or a PanelView.
• It is not a historian. Trends are a rolling buffer, not stored history you can query next month.
• Scripting is a small expression language over tags, deliberately not a programming language.

Questions

Is this SCADA software really free?

The builder is, with no account, no download, no trial period and no tag limit. That last one matters: most free SCADA is free up to a tag count, and the count is chosen to be just below what a real machine needs. There is no count here because nothing is being licensed.

Can I run the HMI without a PLC?

Yes, and that is the point of it. Draw a rung in the free ladder editor, come here, and the screen binds to that program's tags and runs against the same scan engine. A start button on glass starts the motor in the logic, the trend fills and the alarms evaluate, with no controller and no panel present.

How many alarms and tags can I have?

No imposed limit. Alarms follow the ISA-18.2 state machine with deadband, on delay and shelving that expires, and can be generated in bulk from an analogue tag table as a percentage of engineering span rather than defined one at a time.

Can I deploy this to a Siemens or Allen Bradley panel?

No. It designs, proves and documents the screens, and the connection settings are recorded for handover rather than dialled. Export to a panel runtime is the next substantial thing on its list, and it is worth knowing that before you build a plant on it.

What symbols are included?

Eighty seven across twelve categories: vessels, pumps and fans, valves, conveying, heat transfer, instruments, switchgear and pipework, in a flat ISA-101 style or a shaded realistic one. Any of them can be replaced with your own SVG or a photograph of the actual machine.

Does it talk to real plant equipment?

No, and it is not going to. The runtime is the ladder simulator, which is what makes a screen testable at a desk. The driver settings for OPC UA, Modbus TCP, EtherNet/IP or S7 are configured and exported so the design can be handed over, not so that this opens a socket to a machine.