What is an embedded system?
An "embedded system" is an engineering-related term that can vary in meaning by application, who’s using the term, and in what context. Examples of embedded systems are described below, from wide to narrow in areas and architectures as related to and connecting with industrial automation and process controls.
At any of these levels, an embedded system is likely to contain elements of hardware, software, and communications, integrated cybersecurity, and may include one or more control loops (sense-decide-actuate). Embedded systems often run in closed-loop (automated) or in open-loop mode (with human approval or acknowledgement at one or more step).
Embedded systems also can link to or communicate with local or cloud-based connected components, devices, systems, and networks.
Embedded system examples
Value chain or supply chain: Most broadly, embedded systems can operate in and connect various plants and sources within a supply chain (or value chain, as some say), as connected systems of software.
Plant or facility: At the plant level, various departments can have embedded systems. Traditionally, engineering design and procurement may have been in separate silos; interconnection and integration of such systems are increasing.
Plant floor: Maintenance, controls and automation, logistics, engineering systems each are embedded on the plant floor, along with the computers, databases, and communications for each. Power systems also may be considered embedded at this level.
Automation and controls: Embedded systems within automation and controls includes various control systems and controls, across the plant, in the building, fire and life safety, lighting, HVAC, air handling, power, and other systems. These can be discrete control (things) process control (continuous flow), batch control (in tanks or vats), or hybrid control.
Cell level: Within and between various work cells, individual machines and connecting motion controls each can be called embedded systems. In process settings, embedded systems may be considered the controls for the cracker, the fermenter, reactor, or other areas.
Machine level: Within a machine, an embedded system could operate as stand-alone controller, such as an industrial PC (IPC), programmable automation controller (PAC), or programmable logic controller (PLC) outside the machine. Other embedded systems could include networks, machine vision, and other sensors, actuators (motors, valves, pumps), an on-machine or on-process line enclosure or control panel of embedded components, or power system for discrete or process applications.
Device level: Within a device, an embedded system can be the board or the silicon chip providing the logic, the network, power, or sensors especially when each may have their own logic, software, and communications.
Board level: Board-level systems can include sensors, logic elements, and actuators, along with communications. (Unless otherwise specified, most embedded systems, for Control Engineering, are usually at this level.)
Chip level: Once only logic devices, micromechanical systems have brought the embedded systems discussion to the silicon level. Logic is involved with many processors now operating on one chip, and communication systems are involved. Chips also can have gears, actuators, valves, and embedded microsystems. Within embedded memory and instructions (some of it hidden in secure locations), logic can be permanent, such as with an application-specific integrated circuit (ASIC), or changeable, such as with a field programmable gate array (FPGA).
A related semantic challenge
Is the term system integration (singular) or systems integration (plural)? Are we integrating devices within a system or multiple systems in a connected system of embedded systems? Again, it depends. (Usually, Control Engineering says system integration, singular, unless the application would be incorrectly described.)
Going from bottom to top, one can envision how a chip-level embedded system could be part of a board-level embedded system, which could be part of a device level system (in a controller or smart valve), and on up the line. System integration and interoperability gain importance with the need to exchange data for analysis and smarter decisions from embedded system to embedded system among peers or up the line.
Mark T. Hoske is content manager, Control Engineering, CFE Media, firstname.lastname@example.org
KEYWORDS Embedded systems, system integrator
Embedded systems exist on many levels.
Board-level systems often are embedded systems for control engineers.
Do engineers you work with define their terms?
Control Engineering has an embedded systems page under the Control Systems menu.