Field devices or sensors may be signal transmitters, such as level or pressure transmitters. Sensors allow for the immediate retrieval of data from the environment around them—essentially translating operating conditions into information that an industrial system can analyze and utilize. They provide these systems with the ability to react to real-time changes without the need for human observation

Sensor could be discrete signals, such as a valve’s open or closed status, or the motor’s running status. Some devices may actually provide multiple signals. As shown above, the field devices are wired into the Level 1 on the Enterprise hierarchy, which in turn process the signals. can collect data from environmental factors like:

All of the field devices, which are represented by discrete and analog signals, are connected to the various input and output modules of the Controller/PLC. The PLC processes the input signals and effects control through the output signals, based upon the programming in the Controller. Discrete signals can be both input and output types; such signals are two state, meaning the signal can only be in one of two states at any time.

Discrete input signals may include:

Discrete output signals may include:

Analog signals can also be both input and output types; such signals can have a range of values between two preset limits, most often zero and some maximum value. Analog input signals may include:

Analog output signals may include:

Sensors for the Industrial

An Industrial Internet system must be able to minimize the risk of sensor failure through a fault tolerant control system and ensure that system architecture includes appropriate levels of redundancy. If there is a malfunctioning sensor, it should be identified, and if possible, a backup should be brought online. The platform should have a sensor failure detection method that is based on estimating the displacement (or velocity or acceleration) at a sensor’s location using the outputs of other sensors and comparing the estimated value with the sensor’s measurement. Lastly, a system should be in place to predict sensor failure and prescribe a fix with minimal operational disruption and downtime.


Actuators are what manipulate the physical world in an Industrial Internet system. They are a type of motor, and they convert some form of energy into actual movement. Without actuators, data gathered from sensors would have to be acted upon manually, and automation of industrial systems would be impossible. Different actuators might be categorized in a number of ways, including input and/or output energy types, or type of movement (e.g. rotational, trajectional, etc.) Much like with sensors, actuators must be monitored. A fault-tolerant control system must be designed to deal with actuator failures. For instance, the actuator failure detection method can be based on estimating the system input at the actuators’ locations and comparing it with the commands given to the actuators. The design of a fault-tolerant control system depends on the use case and the degrees of freedom in terms of hardware redundancy.

Power consumption

Remote industrial sensors and actuators are expected to operate in some of the toughest environments for extended duration of time, often autonomously. As such, managing power consumption in the overall Industrial Internet system architecture is an ongoing challenge. For example, putting a lot of computing resources on a machine’s multicore processor makes it more selfsufficient, but also requires more local power. In contrast, making the machine dumber (for example, leaving only sensors and a micro controller) may remove the need for CPU-intense local processing, however may result in higher power requirements for data transmission. Since field signals, such as levels, flows and pressures may be used by the program to control the operation of the equipment, the Programmable Logic Controller (PLC) is the heart of the monitor and control of every process area in a SCADA system.SCADA software must consider all of the equipment and signals to be processed.