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Modbus RTU & TCP/IP
Stable industrial communication over RS485 serial or Ethernet — same register map, flexible integration with any Modbus device.
Features
Overview
Reliable, complete and industrial-grade Modbus IO modules. Check out the main features.
A powerful combination of analog and digital inputs and outputs, equipped with everything you would expect from a reliable industrial-grade IO module with Modbus.
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Highlights
What makes Selio industrial-grade
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Optisolated digital inputs
The optoisolation guarantees an extra layer of security and noise immunity.
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Analog inputs at 8 or 12 bit
To capture and measure external variables, such as temperature, pressure etc.
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Output Relays
To command just about anything: electrovalves, inverters, lights and much more.
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Analog outputs
Available both as tension outputs and current outputs.
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On-board buzzer
For acoustic signal, which can be activated through Modbus
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On-board pressure sensor
To precisely and reliably measure pressure.
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Multiple use cases and functions
Use Selio on a variety of applications.
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Product range
Compare 8, 16 and 24 relay models
8
Selio 8 — compact projects / retrofits
16
Selio 16 — a strong balance for many machines
24
Selio 24 — high-density I/O for complex automation
All Selio boards share the same Modbus RTU and TCP/IP communication and core I/O architecture. Choose the relay count that matches your application.
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Specifications
Side-by-side comparison
| Selio features | 8-relay board | 16-relay board | 24-relay board |
|---|---|---|---|
| Inputs | |||
| Digital inputs, optoisolated | 8 (DC / AC) | 8 (DC / AC) | 8 (DC / AC) |
| Analog inputs | 4 (12 bit) | 3 (8bit / 12bit) | 3 (8bit / 12bit) |
| Temperature input | Yes | Yes | Yes |
| Outputs | |||
| Relay outputs | 8 relays | 16 relays | 24 relays |
| Analog voltage | 3 (0-10V, +-10V) | 3 (0-10V, +-10V) | 3 (0-10V, +-10V) |
| Analog current | 1 (4 - 20 mA) | 1 (4 - 20 mA) | 1 (4 - 20 mA) |
| On-board elements | |||
| Buzzer | Yes | Yes | Yes |
| Switches for assigning Modbus registers | Yes | Yes | Yes |
| Pressure sensor | Yes | Yes | Yes |
| LED indicators | Yes | Yes | Yes |
| Reset button* | Yes | Yes | Yes |
| Communication | |||
| Modbus RTU (RS485) | Yes | Yes | Yes |
| Modbus TCP/IP (Ethernet) | Yes | Yes | Yes |
| Can be interfaced with | |||
| PLCs | Yes | Yes | Yes |
| CPUs | Yes | Yes | Yes |
| HMIs | Yes | Yes | Yes |
| Arduino | Yes | Yes | Yes |
| Raspberry | Yes | Yes | Yes |
| Electronic devices (with Modbus)** | Yes | Yes | Yes |
| Power supply | |||
| Voltage range | from 18VDC to 34VDC | from 18VDC to 34VDC | from 18VDC to 34VDC |
| Stand-by power consumption | 120mA @ 24VDC | 120mA @ 24VDC | 120mA @ 24VDC |
| Pre-built libraries | |||
| SelioEasyTest | Yes | Yes | Yes |
Notes
* Reset can also be carried out through Modbus.
** Selio boards can communicate with any Modbus device over RS485 (RTU) or Ethernet (TCP/IP).
Modbus I/O modules are essential for capturing data from sensors and driving actuators with your PLC or custom electronic control. Selio provides a highly versatile, industrial-grade configuration with both serial and Ethernet connectivity — one of the most popular choices for data acquisition and distributed I/O systems.
Documentation
Need the full technical details?
Download datasheets, Modbus register maps, and wiring diagrams from our downloads section.