Editor’s Note: This is a continuation of the education we received from the author who delivered a well received paper in Fasmcro MASTERs.
Many of the benefits and requirements such as low cost, small size, etc are typical of embedded systems in general. Some challenges are more specifically associated with industrial applications. Industrial requirements vary enormously from application to application, but special industrial requirements typically include (Christoffer, 2006; Philip, 1997):
(a) Availability and reliability.
Automation and power systems must have very high availability and be extremely reliable in order to minimize the cost of operation (ie to minimize scheduled as well as unplanned maintenance time).
While customers demand high quality and reliability from most of their embedded systems, it is not necessarily critical if, say, a PDA (personal digital assistant) needs to be restarted after an application causes the system to fail. For industrial applications, however, the effect of a failure in the system could be devastating. A gas leakage at an oil platform, for example, must be detected and followed by a safe shutdown of the process. Otherwise, expensive assets or even human lives could be at risk. Similarly, instabilities in power transmission and distribution networks should be detected before they are allowed to propagate and cause large blackouts. Economic security and personal safety depend on high-integrity systems.
(c) Real-time, deterministic response
‘Real-time’ is a term often associated with embedded systems because these systems are used to control or monitor real-time processes. They must be able to perform certain tasks reliably within a given time. But the definition of ‘real-time’ varies with the application. A chemical reaction, for instance, may proceed slowly, and the temperature at a given point may need to be read no more than once per second. However, the schedule must be predictable. At the other end of the scale, protection devices for high-voltage equipment need to sample currents and voltages thousands of times per second in order to detect and, where necessary, act within a fraction of a power-cycle.
(d) Power consumption
At first glance, the power consumption of industrial electronics may appear insignificant because of the abundance of power that is available. However, this power is not always available, and the need to keep installation costs low has created a demand for electrical protection devices that do not require a separate power supply for the electronics. These devices are self-sufficient with respect to power and meet their needs by extracting small amounts of energy from their surroundings. Wireless sensors for building, factory or process-automation must offer years of battery life or a completely autonomous mode of operation. Self-sufficient power supplies can be designed to extract minute levels of energy from electromagnetic or solar power, temperature gradients or vibration in the environment. This is frequently referred to as energy “harvesting.” Even when power is available, low-power design can be used to reduce the generation of excessive heat that would otherwise necessitate expensive and error-prone cooling devices.
Yet another requirement that is frequently imposed on industrial embedded systems is a long lifetime of the product itself and the life-cycle of the product family. While modern consumer electronics may be expected to last for less than five years, most industrial devices are expected to work in the field for 20 years or more. This imposes challenges not only on the robustness of the electronics, but also on how the product should be handled throughout its lifecycle: Hardware components, operating systems and development tools are constantly evolving and individual products eventually become obsolete.