AI PLC programming can cost nothing per request if you run it on a free model, provided something checks the code before you see it. That is the design of LADX Chat: without a key of your own it runs on free models through LADX's shared OpenRouter account, rate limited per account, and generated code is checked before it reaches the canvas, with the problems listed beside the answer. You can connect your own key to use paid models. LADX itself is free.
For an Indian system integrator or a maintenance team, that changes the question. It is no longer which expensive copilot to buy. It is how to set up a free or low-cost model so that its output is trustworthy enough to review, and what to keep away from it.
What AI PLC programming costs to run
| Setup | What you pay | Limits to know |
|---|---|---|
| Free models (default, no key needed) | Nothing per request | Rate limited per account |
| Your own key (OpenRouter, Anthropic, OpenAI or compatible) | The provider's usage charges, on your account | Billed by the provider, not LADX |
| Local model through Ollama (outside LADX) | Your own hardware and power | LADX cannot use it; speed depends on the machine |
The free route has real limits. OpenRouter's rate limits page said in October 2026 that free model variants allow 20 requests a minute, with a daily cap of 50 requests for accounts that have bought fewer than 10 credits and 1,000 a day once at least 10 have been bought. LADX also rate limits free chat per account on its shared account. For a student or a small team trying ideas, that is plenty. For a busy integrator, your own paid key avoids the wait. Either way, the cost decision is yours and visible on your own provider account, rather than hidden inside a per-seat licence.
Ollama runs open models on your own computer, but LADX cannot use one: its requests go from ladx.ai's server, which cannot reach a model on your machine. Code that must stay on site needs a separate local set-up outside LADX. The browser editor and simulator themselves are free with no account.
Why the checking matters more than the model
General chat assistants write code that looks like ladder logic. Looking right is not the bar when wrong code stops a line. LADX checks generated code and lets the model repair it:
- Generate. The model you connected writes the logic, using the tags already in your project.
- Check. Generated ladder goes through the editor's own validator and a seal-in check. Structured Text is compiled as it arrives by the LADV compiler, LADX's own IEC 61131-3 compiler, alongside a structural check.
- List. Problems are shown beside the answer, not hidden.
- Repair. Auto-fix sends the errors back to the model, up to three times, and shows each attempt.
- Run. Code that passes can be run on a virtual PLC in the browser with one click at ladx.ai/vplc/lab.
That loop is what makes a small free model useful. A weaker model simply needs more attempts, and each attempt is shown. It also keeps the model on your project: LADX passes it the tag names, existing routines, target platform and design basis, so answers reuse the tags you already have instead of inventing new ones. LADX also flags the most common mistake in generated ladder: a seal-in leg that contains only the motor contact, so the motor latches on and the stop button does nothing.
What is Ollama? Running Local LLMs Made Simple
IBM Technology
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Watch on YouTubeWhat checking proves, and what it cannot
A compiler or validator proves code is valid. It does not prove it is correct for your machine. Whether an interlock is enough for the hazard is an engineering judgement that stays with you, and a simulation is not a safety case. LADX also cannot write to a live controller, by design: downloading code to a machine remains a deliberate act by an engineer with the right tools and authority.
Keeping client code private
Indian engineering teams often work under NDAs for overseas clients, so where code goes matters. LADX never sells data or uses it to train AI models, and provider keys are encrypted (AES-256-GCM). On the free tier, the company running the free model may keep prompts and answers, so do not paste client programs covered by an NDA into free chat. LADX has no offline or on-site version, so code that cannot leave the site should stay out of it.
A sensible way for an Indian team to start
- Practise on the free browser editor with a free model, using non-client examples such as conveyors and tank fills.
- Write a short prompt standard: always give the tag table, the target platform and the stop conditions.
- Run every generated routine in the simulator before anyone reads it line by line.
- Keep client code covered by an NDA out of free chat; use your own paid key only if the contract allows it.
- Keep the human sign-off. AI drafts; engineers decide.
LADX is the Wartens group's AI product for controls teams. If you would rather hand the whole job to engineers, our Bengaluru centre delivers turnkey PLC and SCADA projects and trains engineers through edWartens. For moving logic between platforms, read our guide to PLC code conversion for export projects.
Next step: try the loop on a seal-in rung at ladx.ai, or contact us if you want a controls team to review AI-written code before it reaches your panel.
