PLCs (Programmable Logic Controller) are well suited to a wide range of automation tasks. They are typically industrial production processes where changes will be expected over the life of the system. PLCs contain input/output modules and features that are compatible with various industrial environments; in solutions based on PLCs there is very little electrical design, and the problem is basically centered on the design of the desired sequence of operations. PLC-based systems have low costs compared to the cost of a specific custom (ad hoc) controller design. However, the ad hoc solution is more economical when thousands of units are required from the ad hoc device, since non-recurring engineering expenses are spread over thousands or hundreds of thousands of units and the list of components/materials is the same, just and strictly necessary based on the specific requirements of the application for which it has been designed, instead of a generic solution with parts and/or components that will never be used or oversized for our specific application.An ad hoc design would be appropriate where hundreds or thousands of units will be produced, and therefore the development cost (design of power supplies, hardware testing and certification) can be spread over many sales, and the end user is not going to alter the control. Automotive applications are one example, millions of units are built each year, and very few end users alter the programming of these controllers. However, some specialty vehicles, such as transport buses, economically use PLCs instead of ad hoc (custom) controllers, since the volumes are low and the development cost would be uneconomical.However, control of singular or very complex processes may require algorithms, latencies, speeds, deterministic timing and/or high concurrent processing throughputs that easily exceed the capabilities of a PLC, and for which ad hoc -customized- solutions are required, for example, ad hoc solutions could be required in:
- Electrical control devices, such as specific and safety relays for DC and AC electric systems.
- Some chemical processes.
- Flight controls.
- Active safety systems.
- True Real-Time.
- Safety process
- Complex and high performance regarding data-acquition and control.
- Speed and low latency applications.As an intermediate solution, a commercial of the shelf (COTS)-based hardware board like a FPGA-based Single-Board Computer (SBC) can be chosen for control applications that exceed the capabilities of a commercial PLC; with this intermediate solution, the design cost is already amortized and the end development and customization cost is usually perfectly feasible; for which, GENERA Technologies offers suitable solutions.