Blog post 4 : Anatomy of IIoT : Types of Data acquisition

#IIoT #DataAcquisition #Sensors #DataSources

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“In god we trust, all others must bring data” - W. Edwards Deming

Industrial IoT begins with acquiring data from Industrial assets like Diesel generators, Machines in an assembly line, Heavy industrial equipment and so on. In the real world, these industrial assets will be of different makes and models with varying vintages and conditions.

Mechanisms for acquiring data may be readily available in newer assets, however, this may not be the case with older legacy assets.

Acquiring data from these Industrial assets starts with understanding the functioning of the assets, and deciding on the right parameters that need to be measured based on business requirements. Once the parameters are decided, we then get to the crucial step of acquiring the necessary data from these assets. These data can be acquired from different types of data sources.

Some of the common data sources are:

1. Analog sensor data like pressure, temperature, flow, level in the form of 4 to 20 ma[1], 1 to 5v, 0 to 10v, 0 to 20 ma, milli volts ...

2. Binary sensor data ( On/Off ) from proximity, level, limit , pressure switches and so on

3. Sensor data through field protocols like Modbus[2], CANBUS[3]

4. Wireless sensor data from sensors through BLE, Wireless HART ...

5. Data from PLC[4], SCADA[5] systems

6. Data from equipment controllers such as Engine control units, Dedicated controllers used for operating equipment

7. Data from 3rd party cloud platforms through APIs[6]

8. Data from Enterprise systems[7] (Asset master data, Maintenance data, Spares data)

Data acquisition from these multiple data sources can be broadly classified into 4 types as shown below.

1. Direct Sensor Data Acquisition is about acquiring data from standard sensors like pressure, temperature, flow, proximity, level and so on.

2. Derived Measurements are done if direct measurements are not possible due to physical, technological, or cost constraints. This is done by measuring a suitable proxy parameter and deriving the target parameter from this proxy parameter.

3. Data from Industrial control systems like PLCs are extracted through standard field protocols like Modbus, CANBUS, Ethernet/IP, and OPC –UA. Data from SCADA systems can be acquired by using OPC-UA, using IoT platform agents and so on.

4. Data from Equipment are typically acquired through Modbus or CANBUS. These are the most commonly used protocols in equipment Controllers. Modbus is more common in machines used in manufacturing shop floors. CANBUS is used more in Automotive, Off-road, and Mining equipment.

More details about each type of data acquisition are provided in subsequent blog posts.

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[1] ma denotes Milli amps, a standard current output signal from sensors

[2] Modbus is a commonly used serial communications protocol in Industrial applications

[3] Controller Area Network bus or CANBUS is a standard protocol that is widely used in the automotive and heavy equipment industry

[4] Programmable Logic Controller

[5] Supervisory Control And Data Acquisition

[6] Application Programming Interface

[7] In the industrial context, enterprise systems encompass Enterprise Resource Planning systems, Maintenance management systems, Spares management systems and so on