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Introduction
Given the prevalence of PCs in both the office and at home, most of us are familiar the communication ports found on the average PC. USB, Serial, A/V, and Ethernet ports are some of the most common examples that are in use today, enabling users to connect their PC to a network, display, input devices, and more.
Industrial PCs typically include a similar set of communication ports as their consumer-grade counterparts, but what happens when they need to communicate with devices that lack a common port? That is where Digital I/O (DIO) ports come in. DIO ports provide a flexible means of sending data between a PC and any other device that can read a digital “high/low” signal.
To get the most out of a PC’s DIO port, it is important to understand how it’s underlying mechanisms work. Let’s jump in and explore how DIO ports operate, and how to effectively use them in your control system.
What is Digital I/O?
A typical DIO port consists of a series of externally accessible pins for sending or receiving digital signals. The number of pins will vary depending on the manufacturer, with some ports equipped with as many as 20 pins, and others with as few as 8. Depending on the PC model, in some cases the user may be able to configure each pin as an input or output as needed, though some ports divide the pins equally between input and output and do not allow the user to choose.
DIO enables connections with input devices, and sends output to other components such as alarms, actuators, and control relays. The straightforward nature of the DIO port enables the use of hardware configurations and software applications that might not be easily achievable with other common I/O ports such as USB or Serial. This makes DIO an at tractive option for those who have a need for custom solutions to interact with their devices.
Before attempting to use a PC’s DIO port, consult the manufacturer’s documentation to determine the function of each pin. The example below shows the DIO port on the Maple Systems IPC2410A, with 8 pins on the left assigned as inputs, and the remaining 8 pins assigned as outputs.
DIO vs. GPIO
Similar to DIO, the General Purpose I/O (GPIO) port provides a flexible communication port for sending and receiving digital signals. Though they serve largely the same function, the primary difference between DIO and GPIO is that DIO ports are isolated. This isolation adds a layer of protection against high voltage signals coming through, preventing them from damaging connected devices. To accomplish this, an opto-isolator is used to transmit signals between two separate circuits using light instead of a direct electrical connection.
GPIO ports do not utilize isolation and is therefore more vulnerable to voltage spikes and other power events that could cause damage to the system. Additionally, manufacturers equip Digital I/O ports with industrial applications in mind, usually including locking terminal blocks that make the connections more resilient to vibration or shock when compared to a typical GPIO port.
Features
Digital Inputs (DI)
Input pins are used to receive binary signals from external devices. Common examples include sensors, switches, or other devices that provide a high (1) or low (0) signal to the Industrial PC.
Digital Outputs (DO)
Digital Outputs send binary signals from the Industrial PC to external devices. You can use these to control relays, actuators, or other devices that respond to high or low signals.
Voltage levels
Digital signals typically operate at specific voltage levels, such as 0v–3v, 0v-5v, etc. The Industrial PC’s I/O interface must be compatible with these voltage levels, so it is important to review the specs for each device that is going to be connected to the system.
Programming languages
You can control the Digital I/O port through programming languages by creating custom applications for this purpose. This enables automation and real-time control of devices based on received input and can be tailored for specific uses. Software can use Digital I/O ports to control crucial status indicators in factory machinery and to control switches that rapidly count units on production lines.
Applications
The versatility of the DIO port makes it a powerful tool for a variety of applications across several industries. Below are some examples of how DIO ports could be used to extend the base capabilities of an industrial PC.
Security
In the following scenario, the PC serves as part of a security system controlling gate access for a secure site. Upon arrival, personnel encounter a gate that requires a key card to unlock. When scanned, the PC’s database verifies the card’s information, and if valid, lifts the gate.
In this situation, a single PC with a DIO port can replace multiple devices. This PC can read the badge scanner and verify the user using a database. A signal can then be sent through the DIO port to a motor that raises the gate.
In-vehicle
Public transportation vehicles may require video, alarm systems, door controls, and a host of other critical processes to operate. An Industrial PC with DIO is a natural choice for this situation.
For example, the inputs can be used to read door sensors and activate an alarm when a door is open. The PC can simultaneously read signals from push buttons and pull-cords that passengers use to inform the driver to stop. The DIO input can read the button state, and the output will then activate a notification on the driver’s dashboard.
Testing and configuration
Testing and configuring the DIO ports on a PC will require software from the device manufacturer, or a custom application developed by the end user. The manufacturer may include this PC, but if not, review the manufacturer’s support resources or contact them directly to acquire a testing utility.
To help illustrate this process, we have created a demonstration using this Industrial PC as an example. Follow the links below to learn more about the process of configuring and testing the DIO/GPIO ports on an Industrial PC:
Contact us
Would you like to know more? Our friendly and knowledgeable sales team can connect you to the resources you need. For information on pricing, availability, and more, send an email message to sales@maplesystems.com, or contact our team by phone at (425) 745-3229.
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