OT/SCADA & Industrial¶
Vendor Stack¶
11 years of hands-on experience with the industrial control systems used in energy production:
| Category | Vendors / Platforms |
|---|---|
| HMI / Historian | Wonderware (AVEVA), Cygnet |
| DCS | Delta-V (Emerson) |
| RTU / PLC | Roclink (Emerson ROC), various PLC platforms |
| Industrial Radio | Freewave |
| Industrial Networking | Moxa, Hirschmann |
| Measurement | iNet, Orbit, Transnet |
Control System Architecture¶
Field Level¶
- RTUs at wellpads and remote facilities — collecting flow, pressure, temperature, tank levels
- PLCs managing compressor control, artificial lift, safety systems
- Industrial radios (Freewave) providing last-mile connectivity where wired isn't feasible
Network Level¶
- DLR ring topologies — Device Level Ring for resilient industrial Ethernet
- Moxa / Hirschmann managed industrial switches — DIN rail mounted, hardened for extreme temperatures
- IT/OT segmentation — separate VLANs, firewall rules, and monitoring for control system traffic
- Serial-to-IP conversion — legacy Modbus RTU devices brought onto IP networks
Supervision Level¶
- Wonderware / AVEVA — HMI displays, historian, trending, alarm management
- Cygnet — SCADA, measurement, and reporting for oil & gas operations
- Delta-V — DCS for process control at plant facilities
IT/OT Convergence¶
This is the hard part. And it's where most organizations get it wrong.
The IT team wants everything on a flat network with standard patching cycles and cloud-connected management. The OT team needs absolute stability, zero unplanned changes, and network isolation. Both are right. The job is reconciling them.
What Convergence Actually Looks Like¶
- Shared physical infrastructure — same fiber, same microwave links — but logically separated at every layer
- Controlled data flows — OT data moves to IT/business systems through defined, monitored paths. Never the reverse.
- Patching discipline — OT systems get patched, but on a deliberate schedule with tested updates and rollback plans
- Monitoring — IT and OT have different monitoring tools, different baselines, different alert thresholds. Trying to use the same NOC dashboard for both is a mistake.
- Access control — engineers who need to touch HMIs don't need domain admin. Operators who run the SCADA system don't need switch access. Least privilege isn't just an IT concept.
The Purdue Model (Adapted)¶
The ISA-95 / Purdue model still provides the most practical framework for structuring converged networks:
- Level 0-1: Physical process and basic control (instruments, PLCs, RTUs)
- Level 2: Area supervisory control (HMI, engineering workstations)
- Level 3: Site operations (historians, SCADA servers, MES)
- Level 3.5: DMZ — the critical boundary between OT and IT
- Level 4-5: Enterprise IT (business systems, email, internet access)
Every connection crossing the Level 3.5 DMZ has a documented justification, a defined data flow, and monitoring. No exceptions.
Measurement Systems¶
Oil and gas measurement is its own discipline:
- Flow measurement — orifice plates, turbine meters, ultrasonic, Coriolis
- Custody transfer — accuracy requirements for financial transactions between parties
- Regulatory compliance — state and federal reporting requirements
- iNet / Orbit / Transnet — specialized measurement and reporting platforms used across the basin
Real-World Constraints¶
These systems operate in environments that don't forgive bad engineering:
- Temperature — -30°F to 110°F. Electronics, batteries, and communications all behave differently at extremes.
- Power — many remote sites run on solar with battery backup. Power budgets are real constraints.
- Access — 2+ hour drive on unmaintained roads. If something breaks, you want it to either self-heal or be remotely recoverable.
- Safety — these are hazardous environments. H2S, high pressure, rotating equipment. The control systems aren't optional.