เปรียบเทียบ automation architecture

PLC vs DCS vs SCADA
เลือกระบบ Automation ที่ตรงงาน

ตาม IEC 61131-3 (PLC programming) + IEC 61850 (substation comm) + IEC 62443 (cyber security) — architecture, cost, scalability, OEM brands, ทีม engineering ในไทย

คำนวณ Motor + VFD sizing ขอ EPC proposal

สรุปสั้น — โรงงานของคุณต้องการแบบไหน?

เลือกตาม process type (discrete vs continuous) + scale + safety integrity level

Discrete / Machine Control

PLC

Logic + I/O — ทำงาน on/off + sequence
IEC 61131-3 programming (LD/ST/FBD/SFC/IL)
Scan cycle 1-10 ms — fast response
฿80-280K/node — affordable starting point

เหมาะกับ

Packaging machine · conveyor · CNC · sequence control · machine-level automation · OEM equipment

Continuous Process

DCS

Analog loop control — PID + cascade + feedforward
Distributed redundant controllers + HMI built-in
Plant-wide engineering — single project envelope
฿1.5-4M+/controller — large CapEx but proven for safety-critical

เหมาะกับ

Refinery · petrochemical · power plant · pharma · large continuous process · SIL 3+ safety integrity

Supervisory + IoT

SCADA

Reads from PLC/DCS — display + alarm + historian
Multi-site / IoT aggregation
Dashboard + report generation
฿150-400K license — fastest deploy

เหมาะกับ

Multi-factory monitoring · utility (water/electricity) · solar farm · machinery fleet · IoT layer above PLCs

ตารางเปรียบเทียบเต็มสเปก

ตาม IEC 61131-3, IEC 61850, IEC 62443, ISO/IEC 27001 + Thailand industrial market 2026

Parameter	PLC	DCS	SCADA
ฟังก์ชันหลัก	Discrete + sequence control (logic + I/O)	Continuous process control (analog loop)	Supervisory + monitoring + HMI (read+command)
Standard architecture	Standalone or networked, IEC 61131-3 programming	Distributed across plant, redundant controllers	Top layer — reads from PLC/DCS, displays + alerts
Real-time response	Fast (1-10 ms scan cycle)	Medium-fast (100 ms typical)	Slow (1-5 sec, supervisory only)
Scalability	Up to ~10,000 I/O per node	10,000-100,000+ I/O across plant	Unlimited (limited by hardware/license)
Programming standard	IEC 61131-3 (LD, ST, FBD, SFC, IL)	Vendor proprietary + IEC 61131-3 hybrid	JavaScript / Python / vendor scripting
Cyber security	IEC 62443 (level 2-3 typical)	IEC 62443 (level 3-4 required)	IEC 62443 + IT-side (ISO 27001 boundary)
Typical CapEx (per node/loop)	฿80-280K (Siemens S7-1200/1500 + I/O)	฿1.5-4M per controller (ABB/Honeywell/Yokogawa)	฿150-400K license + dashboard (Ignition/Wonderware)
Best fit	Discrete manufacturing — packaging, conveyor, machine control	Refinery, petrochemical, power plant, continuous process	Multi-site monitoring, utility distribution, IoT aggregation
OEM brands ในไทย	Siemens, ABB, Mitsubishi, Omron, Schneider, Allen-Bradley	Honeywell Experion, Yokogawa Centum, ABB 800xA, Emerson DeltaV	Ignition (Inductive), Wonderware (AVEVA), GE iFix, Siemens WinCC
Engineering effort	ปานกลาง — ทีม 1-2 engineer 4-8 สัปดาห์	สูง — ทีม 5-10 engineer 6-12 เดือน	ต่ำ-ปานกลาง — ทีม 1-2 engineer 2-6 สัปดาห์
Saha capability	✅ EPC ครบ — Siemens/Mitsubishi specialists	Partner-supported (large-scale projects)	✅ EPC ครบ — Ignition + InfluxDB stack

Source: IEC 61131-3:2013 · IEC 61850:2020 · IEC 62443:2018 · ISO/IEC 27001:2022 · ARC Advisory Group market data 2024-26

เปรียบเทียบที่เกี่ยวข้อง

ตัดสินใจซื้อ — เทียบหลายมุม

อ่านตารางเปรียบเทียบที่เกี่ยวข้อง — สเปกครบ ราคาจริง พร้อมแนะนำตามงาน

VFD vs Soft Starter vs DOL

Motor control — เลือกตามขนาด motor + load type

Chain Block vs Electric Hoist vs Overhead Crane

อุปกรณ์ยก — เลือกตาม WLL + duty cycle + งบ

Selective vs Drive-In vs Cantilever

Pallet Rack — เลือกตามใช้งาน

FAQ

Common Questions

Q1.PLC vs DCS vs SCADA — what's the short summary?+

PLC = Logic controller (on/off + sequence) for discrete machines. DCS = Distributed Control System for continuous processes (refinery, power plant) — analog loops + redundancy + safety integrity. SCADA = Supervisory layer that READS from PLC/DCS to display dashboards + alerts; doesn't directly control machines. Typical factories use PLC at machine level + SCADA at plant level.

Q2.Does a typical manufacturing plant use PLC or DCS?+

Discrete manufacturing (packaging, conveyor, machine lines) = primarily PLC. Process manufacturing (refinery, chemical, food bulk) = DCS. Medium-scale factories (฿50-200M CapEx) typically use PLC + SCADA combo. DCS becomes economical at scale of 500-1000+ continuous I/O (cost ฿1.5-4M+ per controller).

Q3.What is the IEC 61131-3 programming standard?+

IEC 61131-3 = International Electrotechnical Commission standard for PLC programming languages. 5 languages: LD (Ladder), ST (Structured Text), FBD (Function Block Diagram), SFC (Sequential Function Chart), IL (Instruction List). All major PLC brands (Siemens, ABB, Mitsubishi, Schneider, Omron) support it. Thai government TOR typically requires IEC 61131-3 compliance.

Q4.How is cyber security handled in automation systems?+

IEC 62443 framework (industrial cyber security standard). 5 security maturity levels (SL 1-5). Standalone PLC = SL 2-3 typical. Plant DCS = SL 3-4 required. Use VPN segregation + RBAC + audit log + IT/OT firewall. PLCs must never connect directly to enterprise LAN (DMZ separation). Government work + critical infrastructure require ISO/IEC 27001 + IEC 62443 compliance.

Q5.What's Saha's EPC capability for PLC/SCADA?+

Our team is certified on Siemens + Mitsubishi PLC + Ignition SCADA. Reference: SRT IoT 120+ sensor case study (NB-IoT + SCADA + MQTT + InfluxDB), 18-month deployment with 99.6% uptime. Compliance with IEC 61131-3 + IEC 61850 + IEC 62443 + ISO 27001. Large-scale DCS (ABB/Honeywell) supported via licensed integrator partners. Send us your scope — we'll recommend the right approach.