IoT Architecture/Communication Protocols & Embedded Systems (SCADA)

Internet of things

Edge technology layer

includes all the hardware parts in the IoT system such as sensors, RFID tags, readers, etc. This sensor hardware collects the data for the IoT device.

These sensors can convert the sensory information they capture into data for analysis.

Access gateway layer

where all the data gathered at the edge layer is collected and compressed to an optimal size for analysis.

This is also the point when the data is converted to a digital form. In addition, this layer takes care of message routing, message identification, and subscribing.

Internet layer

the main bridge between two endpoints in an IoT system. It connects devices to other devices, the cloud, the gateway, and backend data sharing.

This layer sends the data to the middleware layer. Some systems may conduct advanced analytics and pre-processing during this stage.

Middleware layer

includes the processes that happen in the cloud such as:

• In-depth processing

• Data management

• Device management

• Data aggregation

• Data filtering

• Device information discovery

• Access control

• Revision for feedback

This layer acts as the interface between the hardware and application layers; that’s why it’s called the middleware layer.

Once all the quality standards and requirements are met, the processed and analyzed data is ready to be sent back to the device.

Application layer

the top layer in the IoT architecture. Its primary responsibility is to deliver the analyzed and processed data to the end user.

The user checks the data and may send commands to the devices or sensors. The process then restarts from the beginning.

Bluetooth Low Energy (BLE)

also known as Bluetooth Smart, is a wireless, personal area network protocol. It supports low-power, long-use IoT needs. It can be used in such sectors as healthcare, security, entertainment, and fitness.

Zigbee

one of the most common short-range IoT communication protocols. Has the following characteristics:

• Is open standard, which means anyone can develop and customize it as needed.

• Has a maximum distance of 60 feet between each hop.

• Allows an unlimited number of hops from a device to the hub.

• Operates at the 2.4 GHz frequency.

Z-Wave

one of the most common short range IoT communication protocol. Has the following characteristics:

• Is closed standard, which means devices must meet specific requirements to be able to use it.

• Has a maximum distance of 250 feet between each hop.

• Can travel only four hops from a device to the hub.

• Operates at the 908.42 MHz frequency.

Embedded systems have the following characteristics:

• Are single-function devices.

• Are static or sealed systems. This means the hardware CANNOT be swapped out.

• Are reactive and make changes in real-time based on feedback from built-in sensors.

• Must be controlled by a microprocessor, have memory, and contain components to connect external devices such as USB ports.

• Use a real-time operating system (RTOS). This operating system handles processes in a deterministic manner.

Key points regarding a RTOS are:

• Different algorithms are used to determine the task that should be performed next.

• Tasks are given individual priority by the program developer, so the RTOS knows the order to perform that tasks in.

• RTOS systems allow for tasks to be processed with almost no latency. This is vitally important for many embedded devices to work properly.

Application-specific integrated circuit (ASIC)

created to perform a single function.

• Are typically custom designed.

• Are used by a company in a single product.

• Have an expensive and time-consuming development process.

• Offer high performance with low power consumption.

System-on-chip (SoC)

incorporates all components on the board, including:

• Processor

• Memory

• Peripheral functions

Field-programmable gate array (FPGA)

physically setup like an ASIC or SoC, but the programming is configured by the end-user. ASIC and SoC chips have the instructions hard coded into them and cannot be changed.

Programmable logic controller (PLC)

a specialized controller that can be programmed to perform specific tasks. Multiple PLCs can be combined and configured to work together to carry out complex tasks.

Supervisory control and data acquisition (SCADA)

can monitor and control PLC systems. They gather data and adjust the system based on the data acquired from sensors.

Human-machine interface (HMI)

can be either a touch-screen control panel or software running on a computer system. Allows the operator to make configuration changes in the system.

Distributed control system (DCS)

a customized all-in-one package that contains the needed PLCs, SCADA controller, and HMI. These are typically custom designed for specific needs.

Modbus

special network protocol that controller systems use to communicate with each other. Originally ran through a serial interface but has evolved to work over Ethernet and TCP/IP.