A connected device (or smart device) is an electronic device, generally connected to other devices or networks, that can operate to some extent interactively and autonomously.
These days, a smart device is generally defined as a device that contains one or more parameters of digital communication networks. Because digital communication requires the use of a microprocessor, today’s smart devices usually provide a wide range of other features as well.
The potential of smart devices
Successful measurement depends on properly selected equipment technology, properly applied in the right application. A simple device is incapable of picking up any information about a process other than the signals transmitted by its direct sensors. In turn, smart devices have the diagnostic capability to detect installation errors or problems relating to a given application, each of which can adversely affect measurement quality and/or reliability. Smart devices are also capable of responding to queries or providing information about the state of the equipment to the automation system, or other platforms operating in the network.
One way to read the information prepared by a smart device is through a user interface. This interface can be a local device monitor, a local portable HMI (human-machine interface), or an HMI network interface. Unlike a local monitor, an HMI display facilitates the exchange of information between the technician or engineer on one side and the device on the other.
The highest class of smart devices are multifunction devices capable of simultaneously capturing multiple process parameters (PVs) using several internal sensors and transmitting data digitally or wirelessly. An example of such a device is a Coriolis flowmeter that measures or calculates mass flow, viscosity, density, temperature, and total volume.
Some smart devices equipped with communication protocols such as HART 6+, WirelessHART, or Foundation Fieldbus H1 can directly exchange process variable (PV) data between similarly equipped devices. These process variables (PVs) are then used to perform additional calculations in the field, without the need for any automation systems or additional ways of performing calculations. For example, a vortex meter can be coupled to a pressure sensor and report corrected energy flow data, or two relative pressure sensors can be combined to capture pressure drop.
The Internet age has opened up a wide range of new possibilities for communication, information management, and access. Although many of these technologies have been adapted to automation platforms, platforms like programmable logic controllers, programmable automation controllers, and distributed control systems, safety and security issues must be considered when connecting critical process control devices via the Internet or related technologies.
Partly because of safety and security concerns, most installed devices still transmit process variable (PV) data to the automation system using traditional 4×20 mA signals that are converted and used in the automation system. However, digital communication systems such as Foundation Fieldbus, Profibus, and Ethernet/IP, and wireless networks such as WirelessHART are increasingly being used to digitally transmit process variable (PV) data directly from the device to automation platforms, eliminating the need for a 4×20 mA electrical signal and associated I/O infrastructure.
Process variables (PVs) that describe energy consumption, transmit environmental information, control electrical circuitry, and process units are typically not part of real-time control systems. Consequently, data about these variables can be delivered directly from smart devices to the appropriate databases via IT-designed access points, greatly simplifying the architecture of automation and information systems.