What hardware features are important when designing an IIoT System?
The Industrial Internet of Things (IIoT) is a subset of the more generalized concept of connected devices known simply as the Internet of Things (IoT). Consumers are the focus of the IoT, with smart appliances offering to change the way we live.
The IIoT is particularly concerned with how smart technologies and connectivity can be used to improve manufacturing facilities and industrial processes. IIoT implementations hold the promise of creating smart factories that are more productive, energy-efficient, and safer than their predecessors.
Both the consumer and Industrial Internet of Things rely on networks of connected devices that generate data that is gathered and processed by computer systems. Consumer implementations use home and personal devices as data points for collecting information intended to make life easier by performing functions such as turning on appliances or conducting remote video surveillance. While the failure of a component in a consumer IoT may be inconvenient for the individuals impacted, they usually do not have any serious effects on society as a whole.
This is not the case with systems that fall into the category of the IIoT. A failure of a system controlling a production line can have dire financial consequences for an entire organization. Even more catastrophic consequences can result from a failed IIoT system designed to control a utility such as a hydroelectric generating plant. In these types of cases, large segments of the population can be put at risk due to a critical system malfunction.
The heightened importance and potential for danger inherent in IIoT implementations demand that a greater level of emphasis be placed on designing more robust systems with stringent safety considerations. In this article, we will discuss the hardware components and their features which are necessary to put together IIoT systems that can withstand the rigors of industrial use.
Sensors and Actuators
The basic infrastructure of an IIoT implementation consists of a network of devices connected together that provide data to control systems and in some cases, can react and perform functions based on instructions returned from the controlling applications. Remote devices in the form of sensors and actuators typically occupy the remote endpoints of the network and are available in a variety of types and styles.
Sensors measure and provide the raw information on which the system depends. Based on the IIoT system under review, the sensors may be measuring environmental conditions such as pressure, temperature, moisture or other important characteristics. The data may just be monitored and analyzed or used to initiate manual or automated processes. Sensors can be broadly categorized based on their data gathering and processing capabilities.
- Base sensors are limited to transmitting the value of the entity they are measuring to the network layer of the IIoT system. They do not have the capability to process the data in any way.
- Smart sensors add functionality that enables them to perform some type of processing on the data before it is passed to the rest of the system. They may include components such as filters, transducers, amplifiers. Embedded software can augment the power of the sensor by transforming analog data reading into digital signals more easily processed by the rest of the system.
- Intelligent sensors ramp up the capabilities of the devices with the addition of the ability to perform self-validation and testing as well as being able to adapt to changing conditions. An intelligent sensor can engage in activities in response to environmental changes it has detected. They employ more advanced computing technologies including machine learning to increase their utility in IIoT implementations.
Actuators are used to take action based on measurements made by the system’s sensors. Actuators can be defined as devices that transform energy into motion. They may be used to trigger alarms or warning systems or to perform critical tasks such as starting or stopping infrastructure components. Some examples are:
- Hydraulic devices responding to liquid measurements;
- Thermal actuators employing a heat source;
- Pneumatic devices generating motion from compressed air;
- Electrical actuators that use external energy sources.
The type of actuator employed is necessarily dependent on the specifics of the IIoT implementation. A common characteristic of actuators is that they need to have the ability to be network-connected and remotely controlled.
Linking sensors and actuators
A programmable logic controller ( PLC) is a digital computer employed to automate electromechanical processes. The code residing on a PLC is developed on a computer and downloaded to the device where it is stored in non-volatile memory. It receives data from connected devices such as sensors and processes the information with its self-contained programming logic. The PLC can then trigger actions based on the information it has received. PLCs are the link between the sensors and actuators in an IIoT environment.
A PLC is comprised of several components including:
- A CPU that performs logical and arithmetic operations;
- Memory that is used for storing and processing data;
- Input and output sections for connecting to sensors and actuators;
- An input to allow programs to be loaded to the PLC.
As with the other components that are used to implement a specific IIoT system, there are many different types of PLCs available. Some important points to consider when selecting PLCs are:
- The PLC needs to have enough I/O slots or cards to handle the number of sensors and actuators that will be connected to the device.
- The computing capabilities of the device need to be able to provide the power needed to drive the system. If you are implementing a system that demands the ability to perform edge-computing, you need to select your PLCs carefully.
- Network connectivity options are another important factor that will inform the PLCs chosen for your system. You may have the capability to use cabled network connections or need to use PLCs that can connect to the Internet wirelessly based on their location.
- The PLC should be compatible with the software and hardware with which it will interact. This includes the communication protocols that are used to transmit data from sensors and to actuators. Many of the sensors that are employed in IIoT implementations use serial connectivity protocols such as RS-232 or Modbus.
How do the components communicate with each other?
The network that connects the components of an IIoT system is vital to its ability to perform its functions. Communication failure in any area of the system can ripple through and cause the entire implementation to malfunction. Some basic questions need to be answered when planning the network with which the parts of an IIoT will communicate.
We touched on this briefly in the discussion of PLCs. The location of the hardware components is the deciding factor in how they will be connected. A self-contained solution that involves monitoring and interacting with a controlled assembly line will, by necessity, demand different methods of connectivity than one that is concerned with a network of wind turbines.
Devices located near each other (e.g. in a manufacturing facility) can connect and communicate with technologies such as Ethernet cables, Bluetooth, RFID, and WiFi. Devices located far apart from one another (e.g. oil pumps scattered all over the country) will need to leverage other communication technologies such as fiber optic cables, 900 MHz radios, or cellular modems.
Regardless of the location of the equipment, all associated devices in the IIoT system need to communicate on the Internet to share data between other hardware and software resources. This can involve transmitting data to a diverse set of on-premises and cloud assets that demand the flexibility to use various communication protocols.
Enabling human interaction in an IIoT implementation
While many aspects of an IIoT system are automated and do not require regular human interaction, there needs to be a way for authorized personnel to gain visibility into its components. Humans also need to be able to assume control of the system in the event of a technology failure or unexpected circumstances that cannot be addressed by the automated procedures and processes.
A human machine interface (HMI) is the primary method through which human operators interact with the IIoT. HMIs come in two forms. The HMI can be embedded in stand-alone equipment or implemented strictly as software running on an industrial-strength computer. In both cases, there may be remote access capabilities built into the solution.
HMIs may indicate status and warning conditions with a visible display or audible signal. Many HMIs are equipped with touchscreens that enable operators to quickly address issues. When selecting the HMI solution that makes sense for a particular IIoT system, you need to consider if remote access is required or if a local interface is sufficient. It may be necessary to use an HMI software package that can be accessed from mobile devices and smartphones to enable responsible individuals to use it from anywhere and at any time.
Ensuring security and safety
Security is vitally important in IIoT systems for several reasons. An IIoT implementation offers hackers many new entrance points into an organization’s networks and computer systems. Every sensor is potentially a gateway to an enterprise’s information resources. Enforcing tight security with firewalls, encryption, strong password protection, and changing default equipment settings is imperative to keep the system safe.
In addition to using the IIoT system to gain entrance into a network, malicious intruders may have more immediately destructive motives. Malware that can manipulate the sensors and actuators or reprogram the PLCs can be used to cause physical damage to the equipment being monitored or controlled by the system. Industrial espionage conducted by coordinated groups or nation-states needs to be taken seriously when developing and implementing an IIoT system.
A final issue is any safety considerations that may need to be implemented around an IIoT environment. Many potentially dangerous situations can occur in systems under the control of an IIoT solution. Safety procedures may need to be put into effect that address the human resources that are exposed to automated equipment if it malfunctions in some way. In extreme cases, such as an out of control power plant, the surrounding population may need to be a part of the safety measures put into place.
There are many moving parts to an IIoT implementation. Selecting the hardware should be done methodically and with an overall design for the system already in place. Putting together an IIoT system piecemeal is asking for trouble. The time and effort spent in planning will pay off in a system that provides the benefits envisioned by the organization when they chose to implement the IIoT.