Houston Refinery
Controls Modernization
See how Controls Foundry helps a real refinery document, analyze, and migrate orphaned PLC programs — from a 30-year-old SLC-500 tank farm to a ControlLogix compressor with undocumented surge logic.
Suction Pressure
62.3psi
Discharge Temp
287°F
Vibration X-Probe
1.8mils
Lube Oil Pressure
38.5psi
What's Running at This Plant
Three equipment systems, three different PLC platforms, zero documentation. A typical brownfield scenario.
C-101 — Centrifugal Compressor
ControlLogix 1756-L75
Main process gas compressor — 5 programs, 30+ rungs covering start/stop sequencing, surge protection, lube oil monitoring, and vibration trip logic.
T-401/402/403 — Tank Farm
SLC-500 1747-L551
Three atmospheric storage tanks with level control, overfill protection, and transfer sequencing. Original program from 1998, no documentation.
F-201 — Flare System
PLC-5/40 1785-L40B
Emergency flare knockout drum and ignition sequencing. Safety-critical — must be documented before any migration work begins.
Live Preview
This is what Controls Foundry looks like when monitoring your equipment.
Signal Dashboard
Discharge Pressure
Suction Pressure
Surge Margin
Discharge Temperature
Drive End Bearing Temp
Non-Drive End Bearing Temp
Vibration X-Probe
Vibration Y-Probe
Annotated Ladder Logic
Master start permissive gate. The operator presses the Start pushbutton, but the motor will only latch into "Start Requested" if the entire safety interlock chain is healthy, the E-stop is not pressed, lube oil pressure is above minimum, and the dry gas seal is pressurized. This is a standard 5-condition permissive pattern.
Operator stop command. Pressing the Stop pushbutton unlatches the start request. This is a simple unlatch — the compressor will coast down through the normal shutdown sequence in the CompressorControl program.
Emergency stop handler. When the E-stop mushroom button is pressed, this rung immediately unlatches both the start request and the running flag, and sets the EStop_Active indicator. This bypasses the normal shutdown sequence — the motor contactor drops out on the next scan.
Load valve command. Opens the load valve after the 15-second stabilization period, but only if suction pressure is within acceptable range. If upstream supply drops (suction pressure too low), the load valve closes to unload the compressor and prevent surge from insufficient inlet flow.
and 11 more rungs annotated...
HMI Process View
How Controls Foundry Works
From unknown PLC program to documented, tested, migration-ready — in three steps.
Upload & Parse
Upload the refinery PLC programs and instantly see what is inside — routines, rungs, tags, I/O points. Works with L5X, RSS, and S7 exports.
Auto-detects Rockwell, Siemens, Mitsubishi, and Omron formats.
Document & Annotate
AI-annotated ladder logic with plain-English descriptions of every rung. Cross-reference explorer shows where every tag is used.
15 rungs pre-annotated with 92% average confidence.
Plan Migration
Map old I/O addresses to new hardware, extract behavioral test cases from recorded sessions, and build a phased cutover plan.
Full I/O trace, recording sessions, and verification dashboard.
Related Reading
PLC-5 to ControlLogix Migration Guide
What your integrator won't tell you about addressing changes, hidden costs, and the undocumented program problem.
Read moreUnderstanding L5X Files
Everything you need to know about Rockwell's L5X export format — structure, tags, programs, and parsing.
Read moreHow to Read an SLC-500 Without RSLogix
Extract and document your SLC-500 programs using modern tools — no Rockwell license required.
Read more