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How to Select the Right Remote I/O for Your Industrial Applications?

How to Select the Right Remote I/O

Data is the foundation of all Industrial Internet of Things (IIoT). Without data, subsequent visualization and analysis would not be possible. Remote I/O modules ensure the operation of field devices and provide various remote data to optimize productivity. It is assumed you have already selected the sensors and devices, and are about to choose your Remote I/O. If this is the case, this article will take you through step-by-step beginning with an  analysis of the advantages of Remote I/O, its physical interfaces, protocols, and I/O functions to choose the right Remote I/O that suits your needs. 

1. What is Remote I/O? What is the difference between Remote I/O and Local I/O?  

Remote I/O usually means that the I/O modules are at a distance from the controllers (PLC/PC), and are installed next to the sensors or actuators to obtain data or send control commands.

Local I/O usually refers to the I/O modules installed in the same cabinet, which can be I/O modules directly connected to the PLC backplane, PCI/PCIE cards installed on the PC, or USB I/O modules used in close proximity.

Local I/O has the characteristics of high-speed and high-density of channels. High-speed measurements that require more than 100K samples/second are usually implemented using Local I/O.

2. When do you need Remote I/O?

Remote I/O modules are the best choice at the following circumstances: 

  • Sensors or actuators are scattered in many places, and it is not possible to configure a set of controllers at each location, which would be too expensive and not efficient. 
  • The distances between controllers and sensors/actuators are long, and hence the signals will be easily disturbed by noise, resulting in increased data errors.

Therefore, deploying Remote I/O close to sensors to transmit data to controllers can greatly reduce wiring complexity, cost, and time. 

Furthermore, the usage scenarios will also affect the selection of Remote I/O because the I/O cycle time will vary greatly in different scenarios. Detailed examples are as below. 

  • Facility monitoring:
    Devices that need facility monitoring often run at a slower I/O cycle time, i.e. 100ms~1,000ms. You can choose Remote I/O modules at this I/O cycle time and they usually go with slower sample rate. 
  • Factory automation, and motion/robotics control: 
    High-speed I/O cycle time is usually required in this scenario as real-time response is critical for machine control. This kind of I/O usually requires a fieldbus to ensure the determination of time. For example, the Remote I/O for the whole factory automation and control usually needs at least 1ms control cycle time, while the Remote I/O for motion and robotics control in the machine requires at least 100 µs control cycle time.

    From the controller's point of view, the most important feature requirement for this kind of Remote I/O is “Real-time”. In other words, each corresponding I/O must report the status in each control cycle to ensure that all input parameters in each control cycle are sufficient for logical operation to produce an output.

3. Determine the physical interface of Remote I/O according to your site conditions

Common Remote I/O physical interfaces include RS-485, Ethernet, Wireless and CAN, and each interface has its own advantages and disadvantages. For example: 

  • RS-485:
    The RS-485 interface has a longer transmission distance and lower cost vs. an Ethernet interface, but the transmission speed is slower. Its maximum number of connected devices is limited. The data from a RS-485 interface has to connect to the gateway before transmitting to the cloud.
  • Ethernet:
    The Ethernet interface is fast and can connect to many devices. The data from Ethernet can be transmitted to the cloud directly through a variety of communication protocols.
  • Wireless (LPWAN/LoRaWAN/WiFi/NB-IoT):
    The wireless interface can be flexibly used in fields where wiring is not possible. Industrial IoT applications, such as factories, energy, and transportation use wireless connections to enable long-distance and low-power transmission.
  • CAN:
    The CAN interface is cost-effective and works with simple wiring. It has high tolerance to noise, and is widely used in telematics environments.

Comparison of different Remote I/O interface:

4. Determine supported IoT protocols of Remote I/O according to your system architecture 

There are many mature communication protocols in industrial automation. The following table lists the widely used IoT communication protocols.

5. Determine Remote I/O functions by sensor/actuator specifications 

According to sensor/actuator specifications and the request of your application, you are able to define analog or digital characteristics for your Remote I/O selection.


Digital Input: 

Digital Output: 

6. After-sale service is key when selecting Remote I/O 

Advantech views customer problems as its own concern and priority, and is dedicated to offering the best after-sale service for customers. The service includes online resources, global customer service and RMA services.

  • Online resources: 
    With 40 years of industry experience, Advantech has collected numerous case studies and technical problems, and turned them into valuable technical FAQ documents on our official website. 

    In addition, our leading IoT on-learning platform, Advantech IoT Academy, provides a diverse selection of video courses covering IIoT general knowledge, product features, hands-on and trouble-shooting videos and certifications to facilitate existing and potential customers. The topics vary from fundamental product training to advanced technical applications.   
  • Global customer service:
    Customers can contact Advantech through live chat or online service requests for 24/7 online service and technical support. 
  • RMA services:
    RMA services repair and fix faulty products from any location and ensure the highest service quality and performance of the products. Advantech provides free repair service or free replacement for defective products during the average 24-month warranty period under normal usage conditions. *Please refer to each product information for its specific product warranty period.

7. Remote I/O applicable industries and scenarios 

  • Factory: Smart Factory Solutions for Tobacco Industries
  • Semiconductor: A Remote I/O Solution Facilitates Data Acquisition for Robots and CVD/PVD Equipment
  • Water & Wastewater: An OPC UA Solution for a Wastewater Treatment Monitoring System
  • Mining: Advantech and PACE Establish a LoRaWAN Solution for General Mining Wellfield Monitoring
  • Infrastructure: High-Speed Distributed DAQ System for Bridge Structural Health Monitoring
  • Oil & Gas: OPC UA Enabled SCADA Monitoring Solution for Gas Stations

8. Conclusion

Selecting the most effective Remote I/O according to your application requires careful consideration and analysis, which will affect subsequent deployment costs, expansion, maintenance, and early prevention of problems.

At the same time, choosing an appropriate supplier is also a major focus which affects the delivery time, guaranteed supply period, product maintenance, technical support and after-sales service.

As an international leader in the design and manufacturing of Remote I/O modules, Advantech provides various communication interfaces, protocols and I/O modules with various functions to meet diverse customer needs, such as facility monitoring, environmental monitoring and industrial-grade process control. When you are evaluating Remote I/O solutions, we are here to provide you with expertise and assistance. Please contact us.

> Related article: 
   How to select the right wireless I/O modules for your applications?