Smart Factories and the Challenges of the Proximity Network
plant workers used handheld probes to take measurements of chicken portions on the process line. To improve process monitoring, the factory replaced manual recordings of the measurements with digital records that would transmit to a centralized database. Given that the probes were handheld, a wireless solution was necessary.
For Predictive Maintenance
The reasoning applied to powering applies even more so to networking. As many of the devices factory and plant operators need monitored for maintenance will have to be retrofitted for monitoring, it is very likely for predictive maintenance edge devices to be wirelessly connected. One case we have seen of this was the desire to monitor an engine of a crane in a ductile iron factory. Giving its inherent movement, connecting a wired sensor to monitor it would have been unfeasible. Instead, the factory placed a wireless, battery-powered vibration sensor on the crane motor and began collecting data to predict when the engine would need servicing.
2.3.3 SENSOR / ACTUATOR INTEGRATION
There are a variety of different physical sensor interface types, such as 4-20 mA, RS-232 and 0- 10 volt with a variety of different protocols for interfacing to sensors and calibration parameters for interpreting the data. The IIoT system architect must decide where and how often the interpretation occurs.
For Process Improvement
The edge device will likely be purpose-built for each application as it will either integrate with an existing interface( such as MODBUS) or be designed as part of a new piece of equipment. The specifics of the application will drive where conversions take place. For example, one factory we toured has a brazing furnace inside of which they want to install a temperature probe. The probe uses a 4-20 mA interface connected to a wireless transmission unit.
For Predictive Maintenance
If the application is a retrofit of existing equipment, then the edge devices likely interface to external sensors, typically via 0-10 V or 4-20 mA connection. Fortunately, most modern factory equipment comes designed via a PLC that can be connected to via MODBUS.
Finding a system that can easily integrate with both existing factory equipment( with PLCs) and new edge device sensors is the key challenge. For example, the crane monitoring solution mentioned previously was part of a larger effort from the factory’ s IIoT architect. The architect needed to ensure that the vibration sensors’ means of transmitting data could easily be funneled into the same database that held the data being collected from many of the factory’ s existing PLCs.
- 68- January 2017