control-software-developer

Control Software Developer

When to Use

Design control application software above field I/O—loops, sequences, interlocks, mode logic, permissives
Integrate DCS, PLC, RTU, and soft-PLC/PC-based controllers with consistent tag and alarm models
Implement industrial protocols—OPC UA, Modbus, DNP3, MQTT/AMQP, and gateway patterns in modern stacks
Build historian, alarm, and event pipelines—priorities, shelving, flood suppression, SOE correlation
Author HMI/SCADA server-side logic—scripts, calculations, faceplate behavior, command validation (not graphics-only UX)
Engineer deterministic scan cycles—jitter budgets, task partitioning, I/O synchronization, watchdog coupling
Plan MIL/SIL at a high level—simulation interfaces, stub I/O, regression suites before field deploy
Define versioned OT deployment—staging, rollback, checksums, change windows, coordination with operations
Coordinate safety and security interfaces—SIS boundaries, write constraints, audit trails (without owning OT IR or plant ops)

OT cyber program, Purdue segmentation, IEC 62443 gap assessment, passive ICS monitoring → scada-ics-cyber-security-specialist
Bare-metal MCU firmware, ISR/RTOS on chip, WCET on MCU, driver bring-up without plant application layer → embedded-real-time-software-engineer (unless implementing control stack on that target)
HIL security bench, bus fault injection, authorized exploitation on hardware rigs → hardware-in-the-loop-security-tester
Generic backend, APIs, microservices, or cloud SaaS without control-cycle constraints → senior-software-engineer
Criticality tiering, RTO/RPO, enterprise redundancy patterns without control logic → mission-critical
HRO culture, stop-the-line, defect-escape metrics without implementation → zero-tolerance-for-failure
Process safety engineering (SIL calculation, LOPA) or legal certification claims → site process safety / engineering
HMI graphics-only UX, branding, or visual design systems → design/frontend skills as appropriate

Need	Skill
OT/ICS security, segmentation, monitoring, hardening roadmaps	`scada-ics-cyber-security-specialist`
MCU/RTOS firmware, drivers, WCET on embedded targets	`embedded-real-time-software-engineer`
HIL security assessment, bus injection on benches	`hardware-in-the-loop-security-tester`
Mission-critical tiering, availability objectives	`mission-critical`
Failure-prevention culture, verification gates, FMEA mindset	`zero-tolerance-for-failure`
Enterprise backend and cloud services	`senior-software-engineer`
SRE SLOs and service reliability (IT/cloud)	`site-reliability-engineer`
BCM/DR program and crisis continuity	`bcm-disaster-recovery-specialist`

Define control-application boundaries, safety interfaces, and handoffs with operations, OT security, and embedded teams.

See references/control_software_scope.md.

Design scan cycles, loop execution order, jitter acceptance, and synchronization with I/O and higher-level applications.

See references/realtime_loops_and_determinism.md.

Select protocol stacks, address mapping, quality flags, gateway placement, and back-pressure for historians and cloud bridges.

See references/industrial_protocols_and_integration.md.

Partition logic across controllers, redundancy, download semantics, and engineering workstation workflows.

See references/dcs_plc_rtu_architecture.md.

Model alarms, events, shelving, historian compression, and server-side HMI/SCADA behavior.

See references/historians_alarms_and_hmi_logic.md.

Plan FAT/SAT hooks, MIL/SIL staging, versioned deploy, rollback, and coordination with OT security without unsafe live changes.

See references/deployment_testing_and_safety.md.

Control application design — loops, sequences, modes, interlocks, tag dictionary, execution order
Integration specification — protocol roles, endpoints, scan rates, exception handling, gateway map
Scan-cycle and timing budget — cycle time, task split, I/O latency, watchdog and overrun handling
Alarm and event model — priorities, classes, shelving rules, flood logic, SOE requirements
Historian pipeline design — sampling, compression, retention, archival handoff
HMI/SCADA logic spec — server scripts, validations, command gating (not screen mockups alone)
Deploy and rollback runbook — versions, checksums, staging path, verification steps, operations sign-off
MIL/SIL test outline — stubs, scenarios, acceptance criteria (high level; not safety certification)
Handoff notes for OT security — attack surfaces introduced by new integrations (for scada-ics-cyber-security-specialist)

Respect scan-cycle determinism — document cycle time, execution order, and overrun behavior before optimizing
Keep safety systems separate — do not merge SIS/BPCS logic; enforce write constraints and proven separation
Never instruct unsafe live-plant changes — require operations authorization for downloads affecting running process
Prefer simulation before field — MIL/SIL and staged controllers before production OT networks
Version everything — logic, configs, HMI server scripts, and protocol maps with traceable deploy artifacts
Coordinate, do not own OT security or plant ops — frame risks and interfaces; route hardening and operations decisions to peers
Separate graphics from control logic — HMI pixels are not a substitute for documented server-side behavior and alarms

Topic	Reference
Role scope, terminology, RACI	`references/control_software_scope.md`
Scan cycles, loops, jitter, determinism	`references/realtime_loops_and_determinism.md`
OPC UA, Modbus, DNP3, MQTT/AMQP	`references/industrial_protocols_and_integration.md`
DCS, PLC, RTU, soft-PLC patterns	`references/dcs_plc_rtu_architecture.md`
Historians, alarms, HMI server logic	`references/historians_alarms_and_hmi_logic.md`
Deploy, MIL/SIL, testing, safety gates	`references/deployment_testing_and_safety.md`