{"id":235,"date":"2023-03-24T11:11:27","date_gmt":"2023-03-24T10:11:27","guid":{"rendered":"https:\/\/cristian-perez.com\/?p=235"},"modified":"2023-03-24T11:11:29","modified_gmt":"2023-03-24T10:11:29","slug":"el-ciclo-scan-en-plcs","status":"publish","type":"post","link":"https:\/\/cristian-perez.com\/en\/el-ciclo-scan-en-plcs\/","title":{"rendered":"The SCAN cycle in PLC's"},"content":{"rendered":"

Para profundizar en los elementos f\u00edsicos referidos a la ciberseguridad industrial y todo lo que tenga que ver con IIOT, empezaremos a explicar como funciona un PLC o automatismo. Para, en posteriores entradas, desarrollar toda un red de seguridad en el \u00e1mbito industrial poco a poco.<\/p>\n\n\n\n

Por recordar un poco conceptos, recomiendo leer la entrada \u00abMicrocontroladores y PLC’s\u00bb<\/a>, donde podremos repasar acerca de diversos conceptos que es importante tenerlos presentes.<\/p>\n\n\n\n

Una vez hecho esto vamos a definir que es el ciclo SCAN<\/strong>.<\/p>\n\n\n\n

El ciclo de SCAN es un proceso que se utiliza en algunos aut\u00f3matas programables (PLC) para controlar y monitorizar dispositivos y procesos industriales. Se refiere al proceso en el que el PLC escanea y procesa la informaci\u00f3n en su programa, desde el inicio hasta el final del ciclo, y luego repite el proceso.<\/p>\n\n\n\n

El ciclo de SCAN se divide en tres fases principales:<\/h2>\n\n\n\n
    \n
  1. Lectura de entradas:<\/strong> en esta fase, el PLC lee el estado actual de todas las entradas que est\u00e1n conectadas a \u00e9l. Las entradas pueden ser interruptores, sensores o cualquier otro dispositivo que detecte un cambio en el estado de un proceso.<\/li>\n\n\n\n
  2. Ejecuci\u00f3n del programa:<\/strong> una vez que se han le\u00eddo todas las entradas, el PLC ejecuta el programa que se ha cargado en su memoria. El programa puede contener instrucciones para controlar dispositivos de salida, como motores, v\u00e1lvulas, luces, etc. El programa tambi\u00e9n puede contener instrucciones para realizar c\u00e1lculos o para tomar decisiones basadas en los valores de las entradas.<\/li>\n\n\n\n
  3. Escritura de salidas: <\/strong>despu\u00e9s de que se haya ejecutado el programa, el PLC escribe el estado de las salidas en funci\u00f3n de las instrucciones que se han dado en el programa. Las salidas pueden ser motores, v\u00e1lvulas, luces, alarmas u otros dispositivos que se utilicen para controlar un proceso, por ejemplo tipo HMI.<\/li>\n<\/ol>\n\n\n
    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    Una vez que se ha completado la fase de escritura de salidas, el ciclo de SCAN comienza de nuevo y el PLC repite todo el proceso de manera constante y en tiempo real.<\/p>\n\n\n\n

    Como hemos visto en el post anteriormente mencionado, sabemos que la velocidad de estos dispositivos es clave, ya que permite ejecutar ciertas tareas, si hiciera falta, en cuesti\u00f3n de milisegundos.<\/p>\n\n\n\n

    Con esto asentamos las bases para entender el siguiente post, que ser\u00e1 acerca de la programaci\u00f3n de los PLC’s, y su comunicaci\u00f3n con los HMI’s. Ya que en este punto es donde se pueden crear sin pretenderlo posibles vectores de ataque, vi\u00e9ndose as\u00ed la infraestructura vulnerada.<\/p>","protected":false},"excerpt":{"rendered":"

    Operation of the SCAN cycle referred to the PLC's<\/p>","protected":false},"author":1,"featured_media":237,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,21],"tags":[24,77,87,58],"class_list":["post-235","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articulo","category-estudios","tag-ciberseguridad","tag-iiot","tag-plc","tag-scada"],"yoast_head":"\nEl ciclo SCAN en PLC's - Cristian Perez<\/title>\n<meta name=\"description\" content=\"Funcionamiento y explicaci\u00f3n del ciclo SCAN referido a los PLC's.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/cristian-perez.com\/en\/el-ciclo-scan-en-plcs\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"El ciclo SCAN en PLC's - 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