If you've been told your facility needs to be "IEC 62443 compliant" and aren't entirely sure what that means in practice, you're not alone. IEC 62443 isn't a single checklist — it's a family of standards for securing industrial automation and control systems (IACS). Here's what actually matters for a plant manager or facility director evaluating it.
IEC 62443 organizes a network into zones — groups of assets that share the same security requirements — and conduits, the defined, controlled pathways that allow communication between zones. Instead of treating a plant network as one flat, trusted space, you group assets by function and consequence: your safety systems in one zone, your supervisory/SCADA layer in another, your enterprise IT in another, and so on.
The point isn't to wall everything off completely — production networks need to talk to enterprise systems for reporting, maintenance, and business operations. The point is that every path between zones is a defined, monitored conduit, not an open, unmanaged connection.
IEC 62443 defines four Security Levels, each representing resistance to a different tier of attacker:
| Level | Protects against |
|---|---|
| SL 1 | Casual or coincidental violation |
| SL 2 | Intentional violation using simple means, low resources |
| SL 3 | Intentional violation using sophisticated means, moderate resources |
| SL 4 | Intentional violation using sophisticated means, extended resources (e.g. nation-state) |
Not every asset needs SL 4. Assigning a security level per zone — based on what happens if that zone is compromised — is what keeps a segmentation project from becoming an unaffordable, over-engineered mess. A warehouse WMS server doesn't need the same security level as a safety instrumented system controlling a chemical process.
The bottom line: IEC 62443 compliance isn't a certificate you buy — it's a design discipline. A network that's genuinely structured around zones, conduits, and security levels is measurably harder to compromise and easier to reason about during an incident, regardless of whether you ever pursue formal certification.
Our Assess and Design stages exist specifically to build this model for your facility — verified asset inventory, zone assignment, security level targets, and a conduit map, before any hardware changes. See our Purdue Model guide for how these zones typically map to the levels of a real plant network.