La memoria y el ciclo de escán son características del procesador. El procesador, también llamado CPU, es la parte más importante del PLC. Este es el encargado de ejecutar todas las tareas para la que fue programado mediante instrucciones y datos que se almacenan en la memoria. La memoria del controlador está dividida en memoria de datos y memoria de programa.
Memoria de datos.
Todas las variables que usa el controlador son almacenadas un área de memoria, llamada memoria de datos. Estas variables son generadas en el controlador. También pueden venir desde el exterior de controlador a través de los módulos de e/s o redes de comunicación conectadas a interfaces de operación o a otros controladores.
En la memoria de datos está la memoria de entrada. En ella se almacena la información de los módulos de entrada digitales y analógicos. También se encuentra la memoria de salida donde se almacenan los datos de los módulos de salida.
Entre los tipos de datos que se almacenan dentro de la memoria de datos se encuentra los booleanos, enteros, punto flotante y cadenas de caracteres.
Algunas instrucciones del controlador usan datos de estructura más complejas como los temporizadores y contadores. Por ejemplo el temporizador al menos necesita un entero que indique el valor final del tiempo, otro que indique el valor actual del conteo y un bit que indique cuando el valor actual alcanzó el valor final. En algunos procesadores estos tres datos se agrupan en un solo dato que se usa con el temporizador. Mientras el conjunto de instrucciones del controlador sea más complejo, hay más tipos de datos que se almacenan en la memoria de datos.
Memoria de programa
Las instrucciones que se colocan de forma ordenada dentro de rutinas para indicar las acciones que va a ejecutar el controlador. El orden en que se colocan las instrucciones depende del tipo de lenguaje usado. En la norma IEC61131 se indican 4 tipos de lenguajes. Estos son: diagrama escalera (LD), diagrama de bloques funcionales (FBD), lista de instrucciones (IL) y texto estructurado (ST). Además, en la misma norma se contempla las cartas de función secuencial (SFC), que es una forma de organizar las rutinas en el controlador, basada en redes de Petri.
Tanto la memoria de datos como la memoria de programa están preservadas de alguna manera con una batería o un condensador. Esto que en ausencia de energía eléctrica, ni los datos ni el programa se pierdan. El controlador tiene al menos un puerto de comunicación que es usado para transferir el programa y los datos.
Ciclo de escán
La ejecución de las operaciones para las que se programó el controlador ocurre de la siguiente manera:
- Lectura de las entradas. Lee la información en los módulos del controlador y se coloca en la memoria de entrada.
- Barrido de rutinas. Ejecutan todas las rutinas en el controlador y actualización de la memoria de datos.
- Actualización de las salidas. Toma la información de la memoria de salida y se escribe en los módulos de salida.
- Comunicaciones. Atiende los requerimientos de comunicaciones.
- Diagnóstico. Verifica si el procesador está funcionando correctamente.
A esta secuencia de operaciones se le denomina ciclo de escán. En los controladores se puede configurar un tiempo de perro guardián, el tiempo que dura el ciclo de escán debe ser menor que el tiempo de perro guardián en caso contrario ocurre un error.
En los PLCs más avanzados las actividades del ciclo de escán no ocurren de forma secuencial. Cada actividad es ejecutada cíclicamente de forma independiente. Algunas de las actividades pueden ser ejecutadas por la aparición de eventos.
tadalafil forum tadalafil generico en mexico
Excellent way of telling, and pleasant piece of writing totake facts on the topic of my presentation subject matter, whichi am going to convey in academy.
Tremendous issues here. I am very glad to peer your article.Thank you so much and I’m taking a look forwardto contact you. Will you please drop me a mail?
Generally I do not read article on blogs, but I wish to say that this write-up very forced me to try and do it! Your writing style has been surprised me. Thanks, very nice article.
I value the article. Really Great.
Thanks for the article post.
Thank you for sharing your thoughts. I really appreciateyour efforts and I am waiting for your further post thank you once again.
A round of applause for your blog post.Much thanks again. Keep writing.
Really appreciate you sharing this post.Much thanks again.
duloxetine hcl uses can duloxetine be augmented with another antidepressant
Great information. Lucky me I ran across your blog by accident (stumbleupon). I have bookmarked it for later.
Pyhlqn – terrorism essay writing Kalnhq ogaupo
Hello there, just became alert to your blogthrough Google, and found that it’s truly informative.I’m going to watch out for brussels. I will appreciate if you continue this in future.Numerous people will be benefited from your writing. Cheers!
Major thankies for the article post.Really looking forward to read more. Keep writing.
Hi, I log on to your blogs like every week. Your writing styleis awesome, keep up the good work!
I like this blog its a master peace ! Glad I discovered this on google .
Hello.This article was extremely motivating, especially because I was looking forthoughts on this issue last Thursday.Here is my blog; xld-zm.com
buy doxycycline tablets – ventolin tablet glucotrol cheap
order augmentin 1000mg pill – brand augmentin 1000mg duloxetine 40mg canada
This really answered my downside, thank you!
Hey There. I found your blog using msn. This is an extremely smartly written article.I’ll be sure to bookmark it and come back to read extra of your helpful information. Thanks for the post.I will certainly comeback.
Hi, after reading this awesome post i am also glad to share my experience here with colleagues.
Wow! This can be one particular of the most helpful blogs We’ve ever arrive across on this subject. Actually Great. I am also a specialist in this topic therefore I can understand your hard work.
Wonderful paintings! That is the type of info that are meant to be shared around the web. Disgrace on the search engines for now not positioning this submit higher! Come on over and consult with my site . Thank you =)
magnificent points altogether, you just gained a new reader. What would you recommend about your post that you made a few days ago? Any positive?
A person necessarily lend a hand to make severely articles I might state. That is the first time I frequented your web page and up to now? I amazed with the analysis you made to make this particular put up amazing. Wonderful job!
I’m very happy to read this. This is the type of manual that needs to be given and not the accidental misinformation that’s at the other blogs. Appreciate your sharing this greatest doc.
Hi my loved one! I wish to say that this post is amazing, nice written and come with approximately all significant infos. I’d like to look more posts like this .
I as well as my guys were found to be digesting the excellent tactics on your site and so the sudden developed a horrible suspicion I had not expressed respect to you for those tips. Most of the ladies were for this reason warmed to read them and now have really been having fun with these things. Thanks for indeed being well thoughtful as well as for selecting variety of brilliant topics most people are really eager to be aware of. Our own honest apologies for not saying thanks to earlier.
lasix without prescription – lasix for sale online cheap betnovate
buy gabapentin 600mg generic – itraconazole where to buy order generic itraconazole 100mg
Hi there! I could have sworn I’ve been to this site before but after checking through some of the post I realized it’s new to me. Anyhow, I’m definitely happy I found it and I’ll be bookmarking and checking back frequently!
Wonderful beat ! I would like to apprentice at the same time as you amend your web site, how can i subscribe for a weblog website? The account helped me a acceptable deal. I were a little bit familiar of this your broadcast offered brilliant transparent concept
Heya i am for the primary time here. I came across this board and I in finding It really useful & it helped me out much. I am hoping to offer something again and aid others like you aided me.
Would you be fascinated by exchanging links?
Hello there! I know this is kind of off topic but I was wondering if you knew where I could find a captcha plugin for my comment form? I’m using the same blog platform as yours and I’m having problems finding one? Thanks a lot!
Is anyone here in a position to recommend Erotic Chocolate Body Paint? Cheers xx
Great wordpress blog here.. It’s hard to find quality writing like yours these days. I really appreciate people like you! take care
Thank you for the good writeup. It actually used to be a entertainment account it.Glance advanced to more brought agreeable from you! By the way, how can we keep up a correspondence?
Appreciate you sharing, great post.Really looking forward to read more. Great.
otc ed pills – dr phil and steve harvey ed pill natural ed pills
There is definately a lot to fiond out about thos subject.I like all of the points you’ve made.
Aw, this was a very nice post. In thought I wish to put in writing like this additionally taking time and precise effort to make a very good article however what can I say I procrastinate alot and in no way appear to get one thing done.
Would you be keen on exchanging hyperlinks?
order omnacortil 10mg generic – purchase azipro pill buy prometrium online
purchase zithromax generic – cheap tindamax 500mg nebivolol for sale online
Asking questions are really good thing if you are not understanding anything completely,but this paragraph offers fastidious understanding yet.Also visit my blog :: 메리트
It’s difficult to find knowledgeable people on this topic, but you seem like you know what you’re talking about!Thanks
I really enjoy the blog. Awesome.
Simply a smiling visitor here to share the love (:, btw outstanding style. «Make the most of your regrets… . To regret deeply is to live afresh.» by Henry David Thoreau.
Oh my goodness! Amazing article dude! Thank you, However I am having troubles withyour RSS. I don’t know the reason why I cannot join it.Is there anybody else having identical RSS issues? Anybody who knows the solution can you kindly respond?Thanx!!
Hi, the whole thing is going fine here and ofcourse every one is sharing data, that’s in fact good, keep up writing.
Greetings! Very helpful advice within this article! It’s the littlechanges that produce the most significant changes. Many thanks for sharing!
Aw, this was a very good post. Finding the time and actual effort to make a great article… but what can I say… I hesitate a lot and never seem to get anything done.
I love what you guys tend to be up too. This kind of cleverwork and reporting! Keep up the very good works guys I’ve incorporated you guys tomy blogroll.
Good day! I could have sworn Iíve been to this blog before but after going through some of the articles I realized itís new to me. Regardless, Iím definitely happy I came across it and Iíll be bookmarking it and checking back often!
Thanks for sharing your thoughts about weight loss programs.Regards
Hi my loved one! I want to say that this article is amazing, great written and comewith approximately all important infos. I would like to peer more posts like this .
Good day! I know this is kind of off topic but I was wondering if you knew where I could find a captcha plugin for my comment form? I’m using the same blog platform as yours and I’m having problems finding one? Thanks a lot!
Thanks again for the blog.Much thanks again. Much obliged.
Thanks so much for the blog post.Really looking forward to read more. Awesome.
Really appreciate you sharing this article post.Much thanks again. Great.
Fantastic blog post.Really thank you! Much obliged.
Im thankful for the article.Thanks Again. Fantastic.
Thanks a lot for the post.Much thanks again. Cool.
Thank you ever so for you blog post.Really thank you! Fantastic.
Htsjrd – cover letter resume Whfkpb vrobod
Wow that was unusual. I just wrote an really long comment but after I clicked submit my commentdidn’t appear. Grrrr… well I’m not writing all that over again. Anyways, just wanted to sayfantastic blog!
amoxil order – how to buy ipratropium combivent 100mcg cost
Hi my family member! I wish to say that this article is amazing, great written and come with almost all important infos. I would like to see extra posts like this .
cost accutane 10mg – cheap linezolid 600 mg linezolid generic
Some truly great info , Glad I noticed this. «Someone’s boring me. I think it’s me.» by Dylan Thomas.
Hey there this is a excellent write-up. I’m going to mail this to my buddies. I stumbled on this while browsing on google I’ll be sure to come back. thanks for sharing.
Thanks-a-mundo for the blog post.Really looking forward to read more. Fantastic.
Some genuinely great info , Glad I discovered this.
stromectol australia – buy ivermectin online order carbamazepine pill
Aw, this was a really nice post. In idea I would like to put in writing like this additionally – taking time and actual effort to make an excellent article… but what can I say… I procrastinate alot and not at all seem to get something done.
Some genuinely interesting details you have written.Aided me a lot, just what I was looking for : D.
Hey, you used to write magnificent, but the last several posts have been kinda boring… I miss your tremendous writings. Past several posts are just a bit out of track! come on!