In an Industrial Internet of Things (IIoT) ecosystem, connected industrial machines use sensors to gather information that informs key decision-makers involved in operating efficiency, maintenance scheduling, and other mission-critical functions. Even though their physical placement is spatially removed from any specific data-aggregation point, sensors represent the front-end edge of the IIoT ecosystem, providing measurements that transform sensed information into quantifiable data such as pressure, displacement, or rotation.
This data can be filtered to connect only the most valuable information beyond the node for processing. All sensors within an edge node must connect through a gateway that links edge data with a network. Low-latency connections allow for critical decisions as soon as the key data is available. This is why the communication from the edge must be flawless for IIoT to reach its maximum potential. This article will explore the connection concepts that enable edge-node communication and the challenges that must be overcome to perfect transmission from the sensor to the network.
The edge node is typically connected to a network, either through a wired or wireless sensor node (WSN). Data integrity remains a key in this block of the signal chain. Optimum sensed and measured data is of little value if the communication is inconsistent, lost, or corrupted. Ideally, a robust communication protocol is prioritized during system architecture design. The best choice will depend on connectivity requirements: range, intermittent vs. continuous connectivity, bandwidth, power, interoperability, security, and reliability.
Wired Connection
Industrial wired communications, such as Ethernet/IP, KNX, DALI, Profinet, and ModbusTCP, are the primary options when connection robustness is paramount. Far-reaching sensor nodes may use a wireless network to communicate back to a gateway that then relies on a wired infrastructure. However, relatively few connected IoT nodes will exclusively use wireline communications. An effective IIoT connection strategy places sensors anywhere valuable information can be sensed, irrespective of where incumbent communications and power infrastructure reside.
Ethernet tends to dominate the wired realm, with IIoT frameworks mapping higher-level protocols on this type of connectivity. Ethernet implementations range from 10 Mb/s up to 100 Gb/s and beyond. The high end generally targets the backbone of the internet to link server farms in the cloud (Kumar 2015).