Industrial Automation

Ethernet I/O Modules for Signal Acquisition and Control via OPC UA and MQTT

Unable to obtain the required data from the PLC? Connect directly to the analogue and digital signals. W&T Ethernet I/O modules read inputs from sensors, contacts, meters and production equipment and make them available to higher-level systems via OPC UA, MQTT, REST or Modbus TCP. Outputs can be controlled through the same interfaces. This allows you to obtain data without modifying the PLC program, often even from an older machine for which no project is available.

Analogue signals 0–10 V and 0/4–20 mA Digital I/O 24 V and relay I/O 230 V OPC UA, MQTT, REST and Modbus TCP Reading inputs and controlling outputs Built-in data logger on selected modules
Help with selecting an I/O module

Which signals do you need to read or control?

We will discuss the signal type and voltage, number of inputs and outputs, required protocol, reading speed, data logging and connection to SCADA, MES, a database or the cloud.

Select a suitable I/O module
More about collecting and controlling signals via OPC UA and MQTT

A machine signal directly into an OT/IT application

An Ethernet I/O module converts a standard electrical signal into data available on the computer network. Instead of modifying the PLC program, you connect the selected signal directly to the module input. A higher-level application then reads it via OPC UA, MQTT, REST or Modbus TCP. For output channels, the application can similarly change an analogue value, switch a digital output or control a relay.

1. Signal source Sensor, contact, meter or machine

Analogue current or voltage, a 24 V digital state, a potential-free contact or a 230 V signal.

2. Signal conversion W&T Ethernet I/O module

The module reads the input, optionally controls the output, and makes the values available over Ethernet.

3. Communication OPC UA, MQTT, REST and Modbus TCP

Standard interfaces enable straightforward connection to industrial and IT applications.

4. Data use SCADA, MES, cloud, databases and alarms

Monitoring, reporting, OEE, energy management, output control and automatic responses.

Which signals can be connected?

Analogue values 0–10 V and 0/4–20 mA

Temperature, pressure, flow, level, speed, position, power, consumption and other continuous variables.

Digital signals 24 V inputs and outputs

Machine running, fault, automatic mode, part pulse, limit switch, pushbutton, valve or signalling.

Mains and relay circuits Relays and 230 V signals

Reading mains states and switching selected loads, contactors, lights or other circuits.

Typical signal sources and targets

  • Analogue temperature, pressure, flow and level sensors.
  • Electricity meters and measuring devices with an analogue output.
  • Auxiliary contacts of relays, contactors and circuit breakers.
  • Running, fault, ready and automatic-mode signals.
  • Pulses from part sensors and counters.
  • Limit switches, pushbuttons and door contacts.
  • Valves, signalling lights and auxiliary relays.
  • Devices requiring an analogue control signal.

What do the modules enable?

Monitoring Continuous input reading

Current analogue and digital values are available over the network without an additional converter or PLC layer.

Control Writing to analogue and digital outputs

A higher-level application can change the output value, switch an output or control a relay.

Data logging Local data logger

Selected analogue modules store measured values in internal memory and allow them to be retrieved later.

Alarms Response to a state or limit value

Depending on the model, an e-mail alert or an automatic output response to an input can be configured.

Long-distance transmission I/O signals over Ethernet

Selected modules can also be used to transmit and synchronise signals between two locations on the network.

Integration Connection without proprietary software

OPC UA, MQTT, REST and Modbus TCP simplify connection to common industrial and cloud applications.

When does direct signal acquisition make sense?

You do not have the PLC program for the machine

You can obtain the required state or analogue value directly from the signal without access to the PLC project.

The machine is under warranty

The data can be added without changing the control program or interfering with the original machine logic.

Retrofitting older technology

An older machine gains an Ethernet interface for monitoring, data logging and transfer to higher-level systems.

Independent energy measurement

Consumption or operating values can be collected independently of the machine control system.

You only need a few signals

For a small number of values, purchasing a PLC or extensive I/O system, or modifying the existing automation, may not be worthwhile.

The output should be controlled by an IT or cloud application

OPC UA, MQTT or REST can switch an output according to a rule in MES, SCADA or a cloud platform.

How do you select the correct module type?

Module type What you can connect Typical use What to watch out for
Analogue 0–10 V Sensors and devices with a voltage signal Process values and analogue control Voltage range, accuracy and active/passive signal
Analogue 0/4–20 mA Industrial current-loop sensors and transmitters Measurement over longer distances and in industrial environments Current-loop power supply and sensor wiring
Digital 24 V PLC signals, contacts, pushbuttons and valves States, pulses and device control Number of DI/DO, output current and common potential
Relay / 230 V Mains signals and relay circuits Switching and monitoring 230 V equipment Maximum voltage, current, contact type and protection

Selected modules

Analogue current 2× AI/AO 0/4–20 mA

Two analogue channels for current signals, configurable as an input or output.

View the 0/4–20 mA module
Analogue voltage 1× AI and 1× AO 0–10 V

Module for reading one voltage input and controlling one analogue output.

View the 0–10 V module
Digital I/O 24 V 12× DI and 12× DO

A larger number of digital inputs and outputs for monitoring and controlling 24 V signals.

View the 12× DI / 12× DO module
Digital I/O 230 V 1× DI and 1× relay DO

Compact module for reading one signal and switching one 230 V relay output.

View the 230 V module
I/O module or a direct Ethernet sensor?

Choose an I/O module when you already have a sensor, meter or device with an analogue or digital output. For a complete network sensor for temperature, humidity, pressure or CO₂, also see Ethernet sensors .

How can FOXON help?

  • We verify the type, voltage and wiring of your signals.
  • We select the appropriate number of analogue and digital channels.
  • We recommend the suitable OPC UA, MQTT, REST or Modbus TCP interface.
  • We assist with module and data-point configuration.
  • We design the connection to SCADA, MES, a database or the cloud.
  • We help with alarms, data logging and output control.
  • We provide testing and commissioning.
  • We provide technical support and assistance with expanding the solution.
Official distribution and technical support: FOXON is a distributor of W&T solutions for the Czech Republic and Slovakia. We assist from selecting the correct I/O module and configuring it through to integrating the data into a higher-level OT or IT system.

Question or Inquiry

Are you looking for a spare part, a repair, one of our products, or do you need to check availability or get advice on a technical solution? Send us the order number, a photo of the nameplate, or a brief description of your request. We will usually get back to you within one hour during business hours.

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