DIO vs GPIO? Key Differences for IIOT Gateways and Edge Computing

With the fourth industrial revolution upon us, a combination of powerful AI computers, energy efficient IIoT ‘Industrial Internet of Things’ Gateways, and remote IIoT devices are being deployed at the edge for interconnecting machines and sensors. Both GPIO (General Purpose Inputs & Outputs) and DIO (Digital Inputs and Outputs) play a key role in connecting edge devices and sensors in the quickly-evolving Industrial Internet of Things model. Allowing for both  local and remote management of systems and devices, Digital I/O helps play a significant role in ensuring effective communication between systems and their operators.

Implementing industrial-grade edge computing allows the process of data at the ‘edge,’ or periphery, close to the originating source. Benefits of capturing and processing data at the source rather than relying on cloud computing includes increased decision making speed with lower latency, higher system reliability with continued operation and optimisation, and lower operational costs as fewer data centres are required to process smaller amounts of data.

As part of Industry 4.0, machine learning models are implemented on devices at the edge to improve the effectiveness of operations through self-learning. This acceleration of dynamic system process optimisation, or Smart Automation, is a step up from simple logic-based control and can help deliver real impact in operational efficiency and innovation.

With a wide range of embedded box computers, single board computers, and industrial motherboards supporting local GPIO and DIO we will discuss key differences with the abilities for both onboard and remote expansion.

General Purpose Input Output, commonly known as GPIO, is a programmable interface that lets embedded controllers send and receive digital signals from IoT sensors, transducers, actuators etc. Despite its name, general purpose refers to the applications for digital signal interface only, they can not be used for accepting analog signals comprising of varying voltages. GPIO pins are commonly used with push fit connectors for input and output channels and an electric current is required in order for them to function properly. The input allows the embedded PC to recognise the IoT device, and then relay command signals through the output. This transfer of information is known as logic signals. These logic signals have two possible values and in general would be represented as either ON or OFF. It is this simple ON/OFF configuration which means other complex protocol such as Serial or USB is not required. GPIO can connect multiple devices simultaneously and is only limited by the channel count and system performance. This means that it has an endless number of uses in general automation and is programmable to best suit the user’s operations.

The main difference between DIO and GPIO is quite apparent in terms of isolation. While both GPIO and DIO can handle a similar channel count, DIO utilises an isolation technique to maintain electrical integrity where as GPIO doesn’t. This additional layer of protection provided by isolated DIO can save machinery failure from electrical events if GPIO was used instead.

Another key difference to note is that GPIO pins are not sustainable on industrial factory floors or environments prone to shock and vibration. This can cause GPIO push fit pins to become loose or disconnected with the sensors or IIoT devices. DIO typically supports locking terminal blocks as a basic requisite and more industrial rugged computers will utilise locking circular M12 connectors for best practice in harsh environments. Maintaining a locked connector makes DIO not only more reliable but ideal for operator switches, machinery status signals and limit switches to name a few use cases.