Reliability, availability, and maintainability (RAM) are three system attributes that are of tremendous interest to systems engineers, logisticians, and users. Software reliability is a separate discipline. Readers interested in software reliability should refer to the IEEE Std 1633 (IEEE 2008). Reliability Engineering Handbook, Volume. BlockSim can resolve even the most complex systems analytically and this method should be used when one is performing reliability analysis. In the context of BlockSim and this reference, we use the term reliability analysis to refer to all analyses that do not include repairs or restorations of the component.

Contents • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Overview Reliability, maintainability, and availability (RAM) are three system attributes that are of great interest to systems engineers, logisticians, and users. Collectively, they affect both the utility and the life-cycle costs of a product or system. The origins of contemporary reliability engineering can be traced to World War II.

The discipline’s first concerns were electronic and mechanical components (Ebeling, 2010). However, current trends point to a dramatic rise in the number of industrial, military, and consumer products with integrated computing functions Because of the rapidly increasing integration of computers into products and systems used by consumers, industry, governments, and the military, reliability must consider both hardware, and software. Maintainability models present some interesting challenges. The time to repair an item is the sum of the time required for evacuation, diagnosis, assembly of resources (parts, bays, tool, and mechanics), repair, inspection, and return. Administrative delay (such as holidays) can also affect repair times. Often these sub-processes have a minimum time to complete that is not zero, resulting in the distribution used to model maintainability having a threshold parameter.

C++ can read these live. Communicate through USB if possible I am comfortable programming the Microcontroller first - plenty of experience using Microchip - Now I would like to use the Arduino - looks like it should be simple enough - direct communication to the board from C++ I have Comport from Winsoft which works well for for my Serial Connection - Sensors / GPS. Would like to be able to read write top the IO pins of the Arduino? Arduino delphi serial communication with arduino board manager. 50 input / output pins.

A threshold parameter is defined as the minimum probable time to repair. Estimation of maintainability can be further complicated by queuing effects, resulting in times to repair that are not independent. This dependency frequently makes analytical solution of problems involving maintainability intractable and promotes the use of simulation to support analysis.

System Description This section sets forth basic definitions, briefly describes probability distributions, and then discusses the role of RAM engineering during system development and operation. The final subsection lists the more common reliability test methods that span development and operation. Basic Definitions Reliability defined as the probability of a system or system element performing its intended function under stated conditions without failure for a given period of time (ASQ 2011). A precise definition must include a detailed description of the function, the environment, the time scale, and what constitutes a failure. Each can be surprisingly difficult to define as precisely as one might wish. Maintainability defined as the probability that a system or system element can be repaired in a defined environment within a specified period of time.

Increased maintainability implies shorter repair times (ASQ 2011). Availability probability that a repairable system or system element is operational at a given point in time under a given set of environmental conditions. Availability depends on reliability and maintainability and is discussed in detail later in this topic (ASQ 2011).

A failure is the event(s), or inoperable state, in which any item or part of an item does not, or would not, perform as specified (GEIA 2008). The failure mechanism is the physical, chemical, electrical, thermal, or other process that results in failure (GEIA 2008). In computerized system, a software defect or fault can be the cause of a failure (Laprie 1992) and the failure may have been preceded by an error which was internal to the item.

The failure mode is the way or the consequence of the mechanism through which an item fails (GEIA 2008, Laprie 1992.). The severity of the failure mode is the magnitude of its impact (Laprie, 1992). Probability Distributions used in Reliability Analysis Reliability can be thought of as the probability of the survival of a component until time t. Its complement is the probability of failure before or at time t. If we define a random variable T as the time te to failure, then where R(t) is the reliability and F(t) is the failure probability, The failure probability is the cumulative distribution function (CDF) of a mathematical probability distribution. Continuous distributions used for this purpose include exponential, Weibull, log-normal, and generalized gamma. Discrete distributions such as the Bernoulli, Binomial, and Poisson are used for calculating the expected number of failures or for single probabilities of success The same continuous distributions used for reliability can also be used for maintainability although the interpretation is different (i.e., probability that a failed component is restored to service prior to time t).