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Remote IO (input/output) is popular in many modern industrial automation systems. Unlike local IO, which is confined to the same cabinet or area as its PLC, remote IO can be placed much closer to the sensors and actuators gathering information. This doesn’t just give control engineers greater design flexibility. It also reduces wiring costs and improves signal strength since remote IO devices can send information directly to PLCs using an Ethernet connection.
In this article, we provide a high-level overview of how to integrate remote IO in a Maple Systems industrial automation network. We’ll outline the hardware and software you need and take a quick look at the logic required to get your system up and running. If you’re still unsure what remote IO is, check out our What is remote IO? article for a detailed breakdown and examples.
What you need to integrate remote IO
Setting up remote IO is similar to configuring local IO in your control cabinet. But instead of attaching local IO modules to a PLC and then wiring each module to field devices nearby, you equip a communication module to the PLC and cable it to a remote IO coupler, which has its own IO modules.

Maple Systems Modular PLC
Integrating a remote IO block into a new or existing network requires a Maple Modular CPU. This compact PLC offers customized expansion options for many control and automation scenarios using our digital, analog, and thermocouple IO modules. To connect the Maple Modular PLC with a remote IO block, you need to equip it with an Ethernet expansion module and connect the two blocks using an Ethernet cable.
Remote IO couplers and modules
To properly connect a remote IO block to a PLC’s Ethernet expansion module, you need a remote IO coupler that matches the communication protocol of your network. Maple Systems’ remote IO couplers support four communication protocols.
- iR-ETN coupler: compatible with Modbus TCP/IP and EtherNet/IP protocols
- iR-COP coupler: compatible with CANopen protocol
- iR-ECAT coupler: compatible with EtherCat protocol
Maple Systems’ remote IO couplers can have up to 16 IO expansion modules attached, making your system highly flexible and scalable. Our iR-ETN40P remote communication coupler even comes with its own built-in digital IO. Maple Systems’ remote IO modules support digital and analog IO, thermocouples, resistance temperature detectors, high-speed counters, and more.
MapleLogic PLC programming software (free)
Our free MapleLogic integrated development environment (IDE) lets developers create and control PLC projects using premade configuration functions and PLC-specific programming languages like Ladder Diagram, Instruction List, Sequential Function Chart, or Function Block. MapleLogic has a robust set of tools and features like detailed monitoring, simulation, tuning, security, and more.
EasyRemoteIO configuration software (free)
Remote IO configuration is traditionally done directly on the remote IO hardware using switches and dials. However, Maple Systems offers software-configurable remote IO modules using EasyRemoteIO software. This free program streamlines remote IO setup by compiling all the IO configuration options you’ll need in an easy-to-use digital interface.
How to connect remote IO
Connect the PLC to the remote IO block
Once you’ve selected the right PLC and remote IO and downloaded the EasyRemoteIO and MapleLogic software, you must physically connect your system. Start by attaching the Ethernet communication expansion module directly to the PLC with any local IO you plan to use. Then, connect the remote IO block to the PLC by running an Ethernet cable from the PLC Ethernet expansion module to the remote IO coupler.
Configure the PLC in MapleLogic
If you haven’t already, you must create a PLC project to control and automate remote or local IO applications. Once you create, test, and simulate your project, you need to designate your system’s device communication hierarchy. In remote IO systems, you must designate the PLC as the master device and the remote IO as the slave device. View our MapleLogic tutorial for step-by-step instructions on establishing that hierarchy.
Configure remote IO in EasyRemoteIO
At this point, you have connected your PLC to a remote IO block, written and created your PLC logic and program, and established the PLC and remote IO as a master-slave setup. Next, you will need to open EasyRemoteIO and set the remote IO coupler’s IP address and configure it for the communication protocol in use. You also must configure any analog IO devices connected by expansion modules. Now you can tune your remote IO modules for your system’s specific needs.
Network topography example
The device and network topography diagram below is an example of a completed control network using a Maple Systems PLC and remote IO. In this example, the PC is used to configure and download a project to the system’s devices. The local and remote IO are connected to the network through an Ethernet switch. Remote IO couplers and PLCs’ Ethernet expansion modules can also connect directly, as shown in the What you need to integrate remote IO section.

Setting up remote IO using CODESYS
CODESYS is a widely used runtime and IDE for creating and running industrial automation and control applications. The CODESYS runtime is typically installed on a PLC, but it can also be used as a software-based PLC (SoftPLC) on a human-machine interface (HMI) or industrial PC (IPC). At its core, a SoftPLC functions the same as a physical PLC but lacks the more advanced processing capabilities of a physical PLC.
Alternatively, SoftPLCs are ideal for network developers who prioritize simplicity because they are easy to develop and deploy, port across hardware and software, and upgrade. Remote IO is a great way to communicate with field devices when using HMIs or IPCs as SoftPLCs, because HMIs don’t include built-in IO, and IPCs often come with a limited amount. Many of Maple Systems’ HMIs can act as SoftPLCs using CODESYS.
First, activate your Maple Systems cMT as a CODESYS device. Once activated, you’ll want to connect your devices through an Ethernet switch and ensure they are running on the same subnet. Similar to setting up remote IO with a physical PLC, you’ll also need to establish the SoftPLC (or the HMI in this example) as the master device and the remote IO as the slave device. Once that’s done, you can open EasyRemoteIO and configure your remote IO application.
View the tutorial below for a detailed breakdown of integrating remote IO using a Maple Systems HMI with CODESYS.
Learn more with Maple Systems
Whether building complex industrial networks or programming your first PLC, Maple Systems has an expansive library of technical and educational resources to support your success. Explore our support pages for tutorials, technical notes, sample projects, and more.
Contact us
Contact our sales team for pricing, availability, and support.
Email sales@maplesystems.com or call (425) 745-3229.

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