Flying Saw PLC Control System: IEC 61131-3 Experimental Setup Guide
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A flying saw PLC control system synchronises a cutting carriage to a continuously moving production line — cutting steel, aluminium, or plastic profiles to length without ever stopping the conveyor. This article walks through the experimental system composition of a modern flying saw PLC setup, updated with 2026 IEC 61131-3 motion control practices, register-cam profiles, and PLCopen function blocks that have reshaped how engineers design, commission, and maintain these high-speed cut-to-length stations.
By KOEED Engineering Team · 2026-06-30 · 12 min read · How-to
Key Takeaways
- A flying saw PLC system comprises PLC CPU, HMI panel, servo drive and motor, encoder, registration sensor, and safety loop — each playing a specific, non-redundant role in synchronised cut execution.
- Modern 2026 implementations use IEC 61131-3 PLCopen function blocks — MC_CamIn, MC_CamTableSelect, MC_TouchProbe — to build electronic register-cam profiles that replace legacy mechanical cam switches and reduce changeover time.
- Jerk-limited Sin-Lin interpolation and online cam switching now allow product-length changes without stopping the line, cutting downtime by up to 40% versus 2024-vintage fixed-cam approaches.
- CODESYS SoftMotion, Beckhoff TwinCAT NC PTP, and Bachmann M-SMC are three widely adopted platforms for flying saw motion control, each offering EtherCAT-based multi-axis synchronisation.
- Adding a digital twin simulation step before physical commissioning reduces cut-length rejects by over 60% in recent field data collected through mid-2026.
Hardware composition, register-cam profile design, PLCopen block wiring, and safety interlocking of a flying saw PLC system — practical tips for engineers in 2026.
1. System Composition Overview
A flying saw PLC control system is not a single device — it is an integrated chain of components that must exchange position data, trigger signals, and safety states within a single control cycle (typically 1–4 ms on EtherCAT). The table below summarises the seven core subsystems and their roles.
| Component | Role in Flying Saw | Typical Spec (2026) |
|---|---|---|
| PLC CPU | Executes motion logic, cam profile selection, and safety interlocks | IEC 61131-3 runtime, EtherCAT master, ≥ 1 ms cycle |
| HMI / SCADA | Operator interface: product recipe selection, cam curve monitoring, alarm log | 7–15 in. touch panel, OPC UA client |
| Servo Drive + Motor | Drives the saw carriage along the linear axis; follows cam profile from PLC | AC servo, 1–7.5 kW, 3 000 rpm, 24-bit absolute encoder |
| Master Encoder | Measures conveyor/line speed — the master reference for cam gearing | Incremental or absolute, 1 024–4 096 PPR, IP65 |
| Registration Sensor | Detects product leading edge; triggers touch-probe latch in PLC for cam phase correction | Laser / photoelectric, < 100 μs response |
| Safety Loop | E-stop, light curtain, safety relay feeding dual-channel inputs to PLC | ISO 13849-1 PL e / SIL 3, FSoE (Fail-Safe over EtherCAT) |
| Fieldbus / Backplane | Real-time communication backbone linking PLC, drives, and remote I/O | EtherCAT (preferred) or PROFINET IRT, cycle jitter < 1 μs |
2. Core Components — What Each One Does
2.1 PLC CPU — The Motion Brain
The PLC is not merely a logic solver; in a flying saw it doubles as a real-time motion controller. Brands commonly deployed include Siemens (SIMATIC S7-1500T with Technology Objects), Allen-Bradley (CompactLogix 1769-L30ER with Kinetix drives), and Mitsubishi (MELSEC iQ-R with Simple Motion modules). In the CODESYS ecosystem, a single runtime handles logic, cam tables, and EtherCAT master duties on one CPU core — reducing hardware count and wiring complexity.
2.2 HMI — Operator Visibility
The HMI displays real-time cam curves, production counters, and alarm logs. In 2026 experimental setups, engineers increasingly use web-based HMIs served directly from the PLC (e.g., Siemens WinCC Unified or CODESYS WebVisu) — eliminating a separate panel PC and cutting BOM cost.
2.3 Servo Drive and Motor — The Muscle
The servo drive receives cyclic position or torque setpoints from the PLC via EtherCAT (CoE — CANopen over EtherCAT) and closes the current/velocity loop internally at 62.5 μs or faster. For a flying saw, the key selection criteria are peak torque for acceleration during the sync phase and continuous torque for the return stroke. Drives from Omron (Accurax G5) and Yaskawa (Sigma-7) dominate Asian-built experimental rigs.
2.4 Master Encoder and Registration Sensor — The Eyes
The master encoder (mounted on the conveyor drive roller or a separate measuring wheel) provides line-speed feedback. The registration sensor detects the leading edge of each incoming product and latches the master position into the PLC via a hardware touch-probe input — this single measurement corrects the cam phase for every cut, compensating for product slip and spacing variation. A typical setup uses a laser through-beam sensor with <100 μs response time wired to a dedicated high-speed input on the servo drive or a distributed EtherCAT slice.
2.5 Safety Loop — Non-Negotiable
A flying saw is inherently dangerous: an exposed blade moving at line speed across a conveyor. The safety loop must include redundant E-stop buttons, a light curtain or safety fence interlock, and a safety relay (or FSoE master) that drops drive enable and triggers Safe Torque Off (STO) in under 10 ms. ISO 13849-1 Performance Level e (PL e) is the expected standard for new installations in 2026.
3. 2026 Motion Control Architecture — IEC 61131-3 + PLCopen
The dominant architecture for flying saw control in 2026 follows the IEC 61131-3 + PLCopen Motion Control model, where axis objects with cyclic interfaces are abstracted from the physical hardware. This standardisation means the same application code — written in Structured Text (ST) or Continuous Function Chart (CFC) — runs across PLC brands with minimal rework.
The core PLCopen function blocks used in a flying saw experimental system are:
| PLCopen FB | Function in Flying Saw | Trigger Event |
|---|---|---|
MC_Power |
Enables the saw carriage servo axis | System start-up, after STO reset |
MC_CamTableSelect |
Selects the electronic cam table (position look-up table) | Recipe change or product-length switch |
MC_CamIn |
Engages the slave (saw) to the master (line encoder) via the selected cam profile | Registration sensor detects product edge |
MC_TouchProbe |
Latches the master axis position on the rising edge of the registration sensor — used to shift cam phase | Hardware latch on sensor trigger |
MC_CamOut |
Disengages the cam — saw returns to home under separate MC_MoveAbsolute | Cut complete (position threshold) |
MC_Home |
References the saw carriage to a known home position | Power-on, after E-stop recovery |
4. Register-Cam Profile — The Heart of Synchronisation
The term "register-cam profile" refers to an electronic cam table that defines the position relationship between the master axis (conveyor line speed) and the slave axis (saw carriage position) across one complete cut cycle. Unlike a mechanical cam, the electronic version can be switched, scaled, or phase-shifted on the fly.
4.1 Four Phases of a Flying Saw Cam Cycle
| Phase | Description | Motion Type | Duration (% of cycle) |
|---|---|---|---|
| 1. Sync | Saw carriage accelerates from home to match conveyor speed; position-locked to master axis | Jerk-limited acceleration (Sin-Lin) | ~25% |
| 2. Cut | Blade traverses the product at synchronous speed; slave velocity = master velocity | Constant-velocity segment | ~20% |
| 3. Return | Saw decelerates, reverses direction, and returns to home position | Jerk-limited deceleration + reverse | ~35% |
| 4. Wait | Saw idles at home; PLC waits for next registration sensor trigger | Zero velocity | ~20% |
In CODESYS SoftMotion and TwinCAT NC PTP, the cam table is defined as an array of master-slave position pairs and then smoothed using polynomial (5th-order) or Sin-Lin interpolation. The cam editor in TwinCAT 3 provides a graphical drag-and-drop interface for tuning the curve — engineers can overlay velocity, acceleration, and jerk profiles to verify that the servo stays within its rated envelope.
> Tip
When designing a cam profile for a flying saw, always set the sync phase acceleration jerk below 50% of the servo drive's rated maximum. High jerk during sync causes overshoot that the registration correction must then compensate for — creating a self-inflicted accuracy loss. Use Sin-Lin interpolation and verify the jerk profile in the cam editor before downloading to the PLC.
5. What Changed Since 2024
The original 2024 experimental system description focused on the basic building blocks — PLC, HMI, servo, encoder, sensors, and safety — as discrete, wired-together components. The 2026 landscape has shifted in five measurable ways:
| Dimension | 2024 Baseline | 2026 Update |
|---|---|---|
| Motion control standard | Proprietary PLC motion libraries, vendor-locked | IEC 61131-3 + PLCopen Part 4 (Coordinated Motion) as de-facto baseline; cross-vendor portability |
| Synchronisation method | Mechanical cam switches or simple electronic gearing (fixed ratio) | Electronic register-cam with online phase correction via MC_TouchProbe; multiple cam tables switchable on-the-fly |
| Motion profile | Trapezoidal velocity (constant accel/decel) | Jerk-limited Sin-Lin interpolation; reduced mechanical shock, longer blade and bearing life |
| Fieldbus | Pulse-train or analog ±10 V to drive; CANopen | EtherCAT CoE with distributed clocks; cycle jitter < 1 μs; single cable for power + data |
| Commissioning | On-machine trial-and-error tuning; risk of mechanical collisions | Digital twin simulation (MATLAB/Simulink or CODESYS SoftMotion virtual axis) before physical run; offline cam validation |
For engineers upgrading an existing rig, the single highest-ROI change is replacing pulse-train drive control with EtherCAT CoE — it eliminates wiring noise issues, enables the full PLCopen motion library, and allows remote diagnostics via OPC UA.
6. Building an Experimental Flying Saw System — Step-by-Step
Step 1: Size the servo axis
Calculate the peak torque required to accelerate the saw carriage mass to line speed within the sync-phase distance. For a typical lab-scale rig (10–20 kg carriage, 1.5 m/s line speed, 0.3 m sync distance), a 750 W–1.5 kW AC servo with a 3:1 belt reduction is adequate. Use the inertia ratio rule: keep J_load / J_motor < 10 for stable tuning.
Step 2: Select the PLC platform
Three practical paths for an experimental setup:
- CODESYS SoftMotion + Raspberry Pi / IPC — lowest cost, full IEC 61131-3 + PLCopen, EtherCAT master via RT-Linux kernel patch. Ideal for university labs and proof-of-concept builds.
- Beckhoff TwinCAT 3 NC PTP — supports up to 255 axes, graphical cam editor, integrated scope for tuning. Requires a Beckhoff IPC or CX-series embedded PC.
- Siemens S7-1500T + SINAMICS S210 — native Technology Objects for camming, integrated safety (F-PLC), TIA Portal engineering. Best fit for industrial pilots that will scale to production.
Step 3: Wire the EtherCAT network
Connect PLC EtherCAT master port to servo drive IN, then daisy-chain to remote I/O slices (high-speed input module for registration sensor + digital outputs for blade clamp and safety relay). Set distributed clocks (DC) so that the servo drive, I/O slice, and PLC share a common time base with <1 μs jitter. Assign the registration sensor input as a TouchProbe source in the drive's CoE object dictionary (0x60B8).
Step 4: Design and load the cam table
Define a 100-point master-slave position LUT for one complete cycle. In CODESYS, use the SoftMotion Cam Editor; in TwinCAT, use the CAM Design Editor. Enable Sin-Lin interpolation. Export the cam as a .CAM file and bind it to MC_CamTableSelect in your PLC program. For a variable-length product, prepare multiple cam tables (e.g., 1.0 m, 1.5 m, 2.0 m cut length) and select via recipe integer from the HMI.
Step 5: Implement the PLC program
Write a state machine in Structured Text with four states: IDLE, SYNC, CUT, RETURN. On a rising edge from MC_TouchProbe, transition to SYNC: call MC_CamIn with the selected cam table. Monitor the slave position; when it passes the cut-end threshold, call MC_CamOut and transition to RETURN (MC_MoveAbsolute to home position). Include a watchdog timer: if the saw does not complete the cycle within 1.5x the expected duration, trigger an alarm and disengage.
Step 6: Commission with digital twin first
Before powering the physical rig, run the cam profile against a virtual axis in simulation mode. In CODESYS, right-click the PLC device and select "Simulation" — the SoftMotion axis will execute the cam table without physical hardware. Verify position traces, velocity, and torque against the servo's rated envelope. Only after the simulation passes should you download to the real PLC and test at low speed (10–20% of rated line speed), gradually ramping up.
Building or upgrading a flying saw system?
KOEED supplies PLC CPUs, servo drives, HMI panels, and I/O modules across Siemens, Allen-Bradley, Mitsubishi, Omron, Schneider, and Yaskawa. Send your BOM to Moritta@KOEED.COM for a consolidated quote — active stock, EOL stock, and cross-references, all in one response within 24 hours.
Send My BOM →7. Platform Comparison for Experimental Flying Saw Systems
The table below compares three commonly used PLC platforms for flying saw experimental setups, evaluated on motion capability, toolchain maturity, and total hardware cost.
| Platform | Motion Library | Max Axes | Cam Editor | Simulation | Relative Cost |
|---|---|---|---|---|---|
| CODESYS SoftMotion | PLCopen Part 1+2+4 | Depends on license | Built-in, polynomial + spline | Virtual axis, offline | $ (lowest) |
| Beckhoff TwinCAT 3 NC PTP | PLCopen Part 1+2+4 | 255 | CAM Design Editor, graphical | Scope 3, virtual axis | $$ (medium) |
| Siemens S7-1500T | Technology Objects (TO) | Depends on CPU | TIA Portal Cam Editor | PLCSIM Advanced | $$$ (highest) |
For an academic or R&D lab, the CODESYS route offers the best value — a single Raspberry Pi 4 with the CODESYS Control for Raspberry Pi SL runtime and a low-cost EtherCAT servo drive (e.g., Leadshine ELP series or Delta ASDA-A3-E) can build a fully functional flying saw testbed for under $2 500 in hardware. For industrial pilots destined for 24/7 production, the Siemens S7-1500T path is more appropriate despite the higher upfront cost, because it comes with integrated safety (F-PLC), OPC UA server, and a well-established spares and support channel through distributors like KOEED.
8. Related Resources on KOEED
- PLC Analog Calculator — convert 4–20 mA and 0–10 V signals to engineering units for your sensor scaling.
- Modbus CRC Calculator — validate Modbus RTU frames when wiring your registration sensor over RS-485.
- Siemens PLC Collection — S7-1500T CPUs, SINAMICS drives, and ET200 distributed I/O for flying saw builds.
- Allen-Bradley Collection — CompactLogix processors, Kinetix servo drives, and PanelView HMIs.
- Mitsubishi Collection — MELSEC iQ-R CPUs and MR-J4/J5 servo amplifiers with SSCNET III/H.
- Omron Collection — SYSMAC NJ/NX machine automation controllers with EtherCAT and Accurax G5 drives.
- KOEED Blog — more engineering notes, migration guides, and How-to articles for industrial automation professionals.
- PLC Error Code Database — cross-vendor fault code reference for quick diagnostics during commissioning.
Frequently Asked Questions
What is a flying saw PLC control system?
A flying saw PLC control system is an automated cutting station that synchronises a moving saw carriage to a continuously running conveyor line. The PLC executes a pre-defined electronic cam profile so the saw matches line speed during the cut, then returns to home position. It is widely used in steel, aluminium, plastic extrusion, and roll-forming lines where stopping the material for cutting is not feasible.
How does a register-cam profile work in a flying saw?
A register-cam profile is an electronic cam table that maps the master axis position (conveyor encoder) to the slave axis position (saw carriage). A registration sensor detects each product's leading edge, and the PLC uses MC_TouchProbe to latch the master position and phase-shift the cam accordingly. This ensures every cut is positioned correctly even if product spacing varies.
Which PLC brands are recommended for a flying saw experimental system?
Three common choices dominate 2026 experimental rigs: CODESYS-based controllers (lowest cost, full PLCopen motion, ideal for R&D labs), Beckhoff TwinCAT 3 NC PTP (graphical cam editor, up to 255 axes, medium cost), and Siemens S7-1500T with Technology Objects (integrated safety, OPC UA, best for industrial pilots). All three support EtherCAT and IEC 61131-3 programming. KOEED stocks CPUs, drives, and HMIs across all three ecosystems.
What changed in flying saw control between 2024 and 2026?
The major shifts are: adoption of IEC 61131-3 + PLCopen motion standards over proprietary libraries; electronic register-cam profiles with online phase correction replacing fixed mechanical cam switches; jerk-limited Sin-Lin interpolation reducing mechanical wear; EtherCAT CoE with distributed clocks replacing pulse-train interfaces; and digital twin simulation enabling offline cam validation before physical commissioning.
Can I retrofit an existing flying saw with IEC 61131-3 motion control?
Yes, in most cases. The key enabler is replacing the legacy pulse-train or analog drive interface with an EtherCAT servo drive. Once the drive communicates via CoE, you can program PLCopen function blocks (MC_CamIn, MC_CamTableSelect) from any IEC 61131-3 runtime. The mechanical saw carriage, blade assembly, and safety hardware can typically be retained — contact Moritta@KOEED.COM for a cross-reference on your specific drive model.
What safety standard applies to flying saw systems in 2026?
New flying saw installations in 2026 are expected to meet ISO 13849-1 Performance Level e (PL e) or IEC 62061 SIL 3 for the safety-related control system. This means dual-channel E-stop inputs, a safety relay or FSoE master that triggers Safe Torque Off (STO) on the servo drive, and a light curtain or interlocked guard that prevents access to the cutting zone during operation.
KOEED Engineering Editorial Team
Industrial automation editors at KOEED. We write about PLC motion control, cross-reference, legacy system support, and experimental system design. For parts sourcing, BOM quotation, or technical consultation, reach the team at Moritta@KOEED.COM.