The development of various microcontrollers has been rapid since their emergence and shows no signs of slowing down. These devices offer a wide range of functions, as well as a cost-effective ecosystem of accessories. Consequently, interest in these products has shifted from small automation companies and robot manufacturers to those in the technology sector who are considering using them in manufacturing.
When engineers seek to solve general industrial automation problems, the traditional approach is to use a programmable logic controller ( PLC ). However, considering the specific factors of different applications, some engineers may also consider using a microcontroller.
In the DIY electronics industry, open-source board-level products derived from microcontrollers, field-programmable gate arrays (FPGAs), and single-board computers have different functionalities and usage limitations. The content discussed in this article falls under the category of microcontrollers. Similarly, PLCs and other industrial controllers, while highly consistent, are not suitable for every type and manufacturer.
For example, an engineer might be considering a small automation task involving two or three sensors, an actuator for output, and a reporting function for a larger control system. It requires a basic program to make it work.
PLCs have been the mainstay in industrial automation applications for decades.
For such simple applications, using a small, inexpensive, open-source board-level microcontroller might be a good choice. Regarding input/output (I/O) compatibility, it's necessary to consider whether the expected microcontroller can provide the required I/O. Finding a suitable number of discrete and analog microcontrollers isn't difficult, but they might not be the right choice.
Some conversions are relatively easy to implement, such as converting a 4-20mA current loop to a 0-5V voltage loop. Other conversions are more difficult, such as using pulse-width modulation (PWM) analog outputs, which is common for microcontrollers. There are some standard signal converters available on the market, but they increase the overall cost. If engineers insist on a complete DIY experience, they might try to create the converter in-house, but this could require significantly more development time.
PLCs are designed to work in conjunction with industrial sensors and have a wide range of I/O modules available, so few, if any, external converters should be needed. Direct connection to the PLC or I/O module becomes easier, as they are specifically designed for this purpose. Built-in isolation for the relevant I/O points ensures a high level of protection for the equipment and circuitry. End users may be able to implement similar functionality, but this requires additional knowledge and increases system complexity.
Since a microcontroller may be a bare board with pins configured for connectivity, encapsulating it in a housing is a good practice. However, the end user must still provide power and create terminals to connect external devices.
Microcontrollers are bare-metal devices, and other factors to consider include: lack of operating system software routines, application programs, and software management functions; software and hardware watchdog functionality; data verification and security modes; environmental factors such as shock and vibration, electromagnetic noise, corrosion, temperature range, and related testing; general-purpose or branded boards; long lifespan and migration paths; technical support; and reliability and security.
