Thomas Brown Controls
Services

PLC engineering and programming for industrial control systems

TBC develops and modifies PLC software around the agreed operating philosophy, I/O and system interfaces, with code structured for testing, diagnosis and controlled change.

PLC software

How the software is structured

The code is organised around operating modes, equipment states and sequence steps so engineers can follow why an output is active, why a command is unavailable and what must happen next.

  • Operating modes and sequence or state control
  • Interlocks and permissives kept clear from equipment commands
  • Alarm and diagnostic handling tied to equipment state
  • Communications, fallback behaviour and revision-controlled backups
Program structureNaming, routines and reusable logic arranged around the agreed operating philosophy.
Equipment controlPumps, valves, motors, packaged plant, switchgear and process equipment handled as understandable control objects.
InterfacesRemote I/O, third-party controllers, HMIs, SCADA and electrical systems tied into defined signal exchanges.
DiagnosticsStatus and fault information exposes the reason for unavailable equipment or interrupted sequences.
Platforms & communications

Established industrial control ecosystems

Platform and protocol selection is confirmed against the project. Manufacturer references describe practical platform experience and do not imply partnership or authorised-integrator status.

  • Siemens SIMATIC and TIA Portal
  • Schneider Electric Modicon
  • Rockwell Automation ControlLogix and CompactLogix
  • CODESYS-based platforms where appropriate
Industrial EthernetNetworked PLC, HMI, remote I/O and package-equipment interfaces.
ProtocolsModbus TCP/RTU, Profinet, EtherNet/IP and OPC UA where required.
MigrationControlled modification or replacement of existing PLC applications.
IntegrationSoftware coordinated with drawings, I/O, SCADA and third-party equipment.
Testing & handover

Software that can be tested, diagnosed and handed over

Testing is based on traceable functional requirements and realistic operating or failure scenarios. Software is proved against simulated or actual I/O, communications and equipment states so the final backup reflects the system that has been tested.

  • Offline simulation before hardware or site testing where practical
  • FAT against approved functional design and test criteria
  • SAT, commissioning, defect closeout and controlled final revisions
FATSequences, permissives, alarms, communications and failure responses.
SATInstalled I/O, networks, equipment interfaces and operating scenarios.
RecoveryStructured fault finding where existing software or interfaces are unclear.
HandoverFinal source files, backups and agreed test evidence under revision control.
Related engineering

PLC engineering only works when the surrounding interfaces are defined.

The software depends on agreed functional requirements, reliable field information and clear responsibility between the PLC and the systems around it. TBC can carry those interfaces through the wider controls package where required.

Functional designModes, sequences, permissives and acceptance criteria agreed before logic is committed.
Electrical & control designSchematics, I/O and field interfaces kept aligned with the PLC application.
SCADA & HMIOperator status, alarms and diagnostics developed from the same control states and signals.
Control systems integrationPLC interfaces coordinated with SCADA/HMI, electrical controls and third-party equipment.

Have PLC logic that needs defining, modifying or recovering?

Send the current software backup, drawings or operating requirement and TBC can establish the safest route through design, modification and testing.

Discuss a project