Two standards, two risks
IEC 61508 and IEC 62443: how they differ.
IEC 61508 covers functional safety: the system must not fail dangerously. IEC 62443 covers cybersecurity: no one should be able to attack or tamper with it on purpose. They complement each other; one cannot replace the other.
Comparison between IEC 61508 and IEC 62443| Aspect | IEC 61508 | IEC 62443 |
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| What it protects against | Random hardware failures and systematic design or software errors. | Intentional actions: attacks, unauthorized access, malware and tampering. |
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| Level it defines | SIL 1 to 4 (Safety Integrity Level). | SL 0 to 4 (Security Level). |
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| How the level is measured | Probabilistic. In low demand mode, SIL1 requires a PFD between 10⁻² and 10⁻¹ and SIL2 between 10⁻³ and 10⁻². In continuous mode, PFH per hour is used. | Not probabilistic. It depends on the attacker's capability: SL1 covers casual errors or access, SL2 an intentional attack with simple means, and SL3 and SL4 attackers with resources and specific knowledge of industrial systems. |
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| Typical tools | Risk analysis (HAZOP, LOPA), hardware fault tolerance (HFT), diagnostic coverage, safe failure fraction (SFF) and systematic capability. | Zones and conduits, 7 foundational requirements (authentication, integrity, confidentiality, among others) and a secure development lifecycle. |
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| Structure | Generic standard in 7 parts, with sector standards derived from it: IEC 61511 for process and IEC 62061 / ISO 13849 for machinery. | Organized by role: asset owner (series 2), integrator (3-2 and 3-3) and product supplier (4-1 process and 4-2 component). |
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IEC 62443 in FCX
The 7 foundational requirements, applied.
IEC 62443 organizes industrial cybersecurity into seven foundational requirements (FR). This is how we address them in FCX.
- FR 1 Identification and authentication control
- Maintenance access requires authentication and automatically blocks repeated failed attempts. The operator account does not allow password login.
- FR 2 Use control
- Operators work with an unprivileged account, on a kiosk-mode screen that gives no access to the system. Up to 10 user levels, with unlimited users per level, so each person sees and operates only what is theirs.
- FR 3 System integrity
- Read-only base system, software reduced to the minimum and an isolated interface where nothing can be added or installed.
- FR 4 Data confidentiality
- Operator interface over HTTPS, with no telemetry, no sync and no external accounts.
- FR 5 Restricted data flow
- All incoming traffic blocked by default; only the ports the process needs are enabled, within the plant's zones and conduits.
- FR 6 Timely response to events
- Installation, boot and access logging, and automatic blocking of sources that try to force access.
- FR 7 Resource availability
- Memory without swap and with a guaranteed reserve, no suspend or hibernation, and automatic restart of the interface after a failure.
IEC 61131-3 programming
Object-oriented, to IEC 61131-3.
FCX software is designed with object-oriented programming to IEC 61131-3, the international standard for programming controllers: orderly, reusable code that does not depend on one manufacturer.
Open standard
Languages and structure are defined by the standard, not by a brand: the control can be read and maintained without depending on a hardware vendor.
Each machine, an object
Compressors, chillers, valves and evaporators are programmed as objects with their own logic. They are tested once and reused in every plant.
Inheritance and interfaces
Equipment variants inherit what they share and add what is specific: expanding the plant does not mean rewriting the control.
Deterministic tasks
The program is organized in tasks with a defined cycle and priority, so each part of the process responds on time.
Strictly typed data
Defined types and ranges catch out-of-place values at design time, not in the plant.
A base for SIL and SL
Modular, traceable and verifiable software is the foundation IEC 61508 and IEC 62443 call for.
Virtualized control
FCX also runs on virtualized control servers.
We have spent 30 years developing software-based industrial control. Ten years ago we began migrating to CODESYS, with object-oriented programming, in pursuit of safe and reliable systems. That experience lets us run FCX on virtualized plant servers, in containers or on a hypervisor, with the same control logic and the same security rules.
Several controllers on one server
Each process runs in its own control instance, isolated from the others. Less hardware, less wiring and fewer panels to maintain.
Predictable control cycle
We define the platform and each instance's reserved resources so control responds on time even when it shares the server.
Field devices over industrial Ethernet
Field equipment connects over the industrial network, just as with a physical controller.
Centralized maintenance
Updates, backups and new functions are managed from the server, without working panel by panel.
Each instance, one zone
Each instance is treated as an IEC 62443 zone, with its own access and traffic control. SIL functions stay on dedicated safety hardware.
Availability by design
We plan server and storage redundancy so control does not depend on a single machine.
