L’automatisation ne rend pas forcément le test logiciel plus rapide, plus fiable ou moins onéreux. Les coûts initiaux liés à la configuration et aux outils d’automatisation pouvant être élevés, l’automatisation des tests n’est profitable que si les coûts à long terme compensent ces dépenses initiales. En outre, les outils et méthodologies d’automatisation ne possèdent pas tous les mêmes caractéristiques, fonctionnalités et capacités, et chaque projet peut répondre à des exigences différentes, ce qui a des répercussions sur les coûts et les bénéfices.
Pour automatiser vos campagnes de marketing, comptez un budget de plusieurs centaines d’euros. Ce budget inclut la réflexion stratégique sur le contenu de la campagne, les compétences techniques nécessaires à son automatisation et l’installation de logiciels si nécessaire. Le coût est bien entendu variable selon ce que vous souhaitez automatiser. Il reste important de noter que cette technique est aussi source de gain de temps et de clients !
Starting in 1958, various systems based on solid-state digital logic modules for hard-wired programmed logic controllers (the predecessors of programmable logic controllers (PLC)) emerged to replace electro-mechanical relay logic in industrial control systems for process control and automation, including early Telefunken/AEG Logistat, Siemens Simatic (de), Philips/Mullard/Valvo (de) Norbit, BBC Sigmatronic, ACEC Logacec, Akkord (de) Estacord, Krone Mibakron, Bistat, Datapac, Norlog, SSR, or Procontic systems.
With the advent of the space age in 1957, controls design, particularly in the United States, turned away from the frequency-domain techniques of classical control theory and backed into the differential equation techniques of the late 19th century, which were couched in the time domain. During the 1940s and 1950s, German mathematician Irmgard Flugge-Lotz developed the theory of discontinuous automatic control, which became widely used in hysteresis control systems such as navigation systems, fire-control systems, and electronics. Through Flugge-Lotz and others, the modern era saw time-domain design for nonlinear systems (1961), navigation (1960), optimal control and estimation theory (1962), nonlinear control theory (1969), digital control and filtering theory (1974), and the personal computer (1983).
An early development of sequential control was relay logic, by which electrical relays engage electrical contacts which either start or interrupt power to a device. Relays were first used in telegraph networks before being developed for controlling other devices, such as when starting and stopping industrial-sized electric motors or opening and closing solenoid valves. Using relays for control purposes allowed event-driven control, where actions could be triggered out of sequence, in response to external events. These were more flexible in their response than the rigid single-sequence cam timers. More complicated examples involved maintaining safe sequences for devices such as swing bridge controls, where a lock bolt needed to be disengaged before the bridge could be moved, and the lock bolt could not be released until the safety gates had already been closed.
Relay logic was introduced with factory electrification, which underwent rapid adaption from 1900 though the 1920s. Central electric power stations were also undergoing rapid growth and operation of new high pressure boilers, steam turbines and electrical substations created a large demand for instruments and controls. Central control rooms became common in the 1920s, but as late as the early 1930s, most process control was on-off. Operators typically monitored charts drawn by recorders that plotted data from instruments. To make corrections, operators manually opened or closed valves or turned switches on or off. Control rooms also used color coded lights to send signals to workers in the plant to manually make certain changes.