FIRGELLI engineering guide
Most electric linear actuators do not need an industrial network. Many only need polarity reversal through a rated switch, relay or actuator controller. Other machines need position commands, diagnostics, synchronized motion or PLC integration.
This guide explains where simple DC control ends and smart actuator control begins, so the system is not under-specified or made unnecessarily complex.
Key Engineering Takeaways
- A two-wire DC actuator usually extends and retracts by reversing polarity.
- PLCs normally need a relay, motor driver or controller between the PLC output and the actuator motor.
- Feedback is not the same as a smart network interface.
- CAN, IO-Link and Modbus only help when the actuator or controller actually supports them.
- Smart interfaces can add diagnostics, parameter setting and position commands, but they add integration work.
- Start with compare actuator control boxes or use the FCB-2 actuator controller before jumping to a networked architecture.
Engineering Guide
1. Simple DC control
A basic brushed DC linear actuator is controlled by polarity reversal. Apply 12 VDC or 24 VDC one way and it extends. Reverse polarity and it retracts. Internal limit switches usually stop motion at the ends of travel.
That simple behavior is useful. It keeps cabinets, hatches, vents, doors and light industrial motion easy to wire and maintain. The control system still needs current capacity, fusing, wire size and safe switching.
For simple wiring, use wire a linear actuator to a switch and use the FIRGELLI wiring diagram guide before building the harness.
2. PLC control is not the same as driving the motor directly
Most PLC outputs cannot power an actuator motor directly. The PLC commands a relay, H-bridge, motor driver or actuator controller that is rated for motor current. The controller then handles direction, speed, feedback or synchronization depending on the design.
The PLC also needs useful status information. That may be end-of-travel switches, current state, position feedback, fault output, or a networked diagnostic value from a smart controller.
Use integrate electric actuators with PLCs and connect optical feedback actuators to PLC or Arduino when the actuator has to fit into an automation cell.
3. CAN, IO-Link and Modbus
Industrial interfaces can reduce wiring and add diagnostics, but they are not universal translator boxes. The actuator or controller must support the protocol, the network must match the PLC or gateway, and the data map must expose the commands and feedback the machine needs.
IO-Link is often used for point-to-point device communication into industrial networks. CAN is common in mobile and vehicle systems. Modbus is common in industrial control. Each choice affects wiring, commissioning and troubleshooting.
If the project needs networked control, compare control actuators from alternative networks and choose Arduino, Raspberry Pi or microcontrollers for actuator control before selecting hardware.
4. Actuator example: automated production changeover
A production line changeover axis may need saved positions, slow approach speed and a fault signal if the actuator cannot reach position. A simple switch is not enough. A feedback actuator with a controller may be enough for a standalone station, while a PLC-connected system may need a controller that exposes position and faults to the line control system.
Where closed-loop control is needed, use tune a discrete PID controller as a design reference and confirm the actuator feedback type before coding the PLC.
Specification Checks
| Check | What it means | Engineering note |
|---|---|---|
| Switch or relay | Simple extend/retract control. | Good for full-travel motion. |
| Actuator controller | Speed, timing, feedback or synchronization. | Useful before adding PLC complexity. |
| PLC plus driver | Machine-level control with external motor driver. | PLC output must not be overloaded. |
| CAN/IO-Link/Modbus | Networked commands and diagnostics. | Only works with supported hardware and data maps. |
| Feedback actuator | Position signal to controller. | Feedback is not automatically a network interface. |
Field Checklist
- Required motion: full extend/retract or controlled position
- Supply voltage and actuator current
- Control device current rating
- Feedback type and controller input
- Need for synchronization
- Need for saved positions or timed moves
- Need for diagnostics or fault output
- PLC output type and isolation
- Network protocol support
- Commissioning and troubleshooting access
Common Mistakes
| Mistake | Why it causes problems | Better practice |
|---|---|---|
| Driving the motor from a PLC output | The output is overloaded. | Use a motor driver, relay or actuator controller. |
| Buying a smart actuator without a data plan | The protocol exists but the needed variable is not exposed. | Check the data map before ordering. |
| Adding a network to a simple job | The system becomes expensive and harder to service. | Use simple DC control when full-stroke motion is enough. |
Frequently Asked Questions
Can I control a linear actuator directly from a PLC?
Usually not directly. Most PLC outputs are command signals, not motor-power outputs. Use a relay, H-bridge, actuator controller or motor driver rated for the actuator current.
What is the simplest way to control a linear actuator?
For full extend and retract motion, reverse polarity to a two-wire DC actuator using a rated switch, relay or controller.
When do I need feedback control?
Use feedback when the application needs saved positions, synchronized actuators, repeatable partial travel, position display or closed-loop control.
Is IO-Link useful for linear actuators?
It can be useful in industrial automation when the actuator or controller supports IO-Link and the machine needs parameter setting, position commands or diagnostics through the control network.
Is CAN bus better than Modbus for actuators?
Neither is universally better. CAN is common in mobile equipment; Modbus is common in industrial controls. Choose the protocol the machine already supports and the actuator/controller can actually speak.
Can the FCB-2 replace PLC control?
The use the FCB-2 actuator controller can handle many actuator-control jobs such as timed operation, speed control and synchronized systems depending on actuator type. A PLC is still better when the actuator is one axis in a larger machine-control sequence.
What should I check before buying a smart actuator?
Confirm voltage, current, force, stroke, protocol, data map, controller compatibility, cable requirements, diagnostics and how faults will be handled.
