Contrôler l'action #5
⚡ TOUTES LES INFORMATIONS CLIQUEZ ICI 👈🏻👈🏻👈🏻
Contrôler l'action #5
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
2022 © Reproduction without explicit permission is prohibited. - PLC SCADA Courses - Engineers Community
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Air to open/close valves and direction of control action
Control valves come in two sorts: air to open; and air to close.
Air to open valves are normally held closed by the spring and require air pressure (a control signal) to open them – they open progressively as the air pressure increases.
Air to close valves are valves which are held open by the valve spring and require air pressure to move them towards the closed position.
The reason for the two types of valves is to allow fail safe operation. In the event of a plant instrument air failure it is important that all control valves fail in a safe position (e.g. an exothermic reactor’s feed valves (or, perhaps, just one of the valves) should fail closed (air to open) and its coolant system valves fail open (air to close)).
The type of valve used obviously impacts on what a controller has to do – changing the type of valve would mean that the controller would need to move the manipulation in the opposite direction.
To simplify things in this course we shall assume that we are always using air to open valves – an increase in control action will cause the valve to open and the flow through it to increase.
The other important thing you need to understand is the direction of control action. Consider the system shown in the diagram.
In this process I have connected a level controller to the bottom valve. For this configuration the controller needs to increase its signal (and hence the flow) when the level in the tank increases.
In this case the controller needs to reduce the flow when the level in the tank increases.
Both configurations are equally capable of controlling the level, but they require the controller to do entirely opposite things. This is what direction of control action involves.
A direct acting controller is one whose output tends to increase as the measurement signal increases.
A reverse acting controller is one whose output tends to decrease as the measurement signal increases.
All control systems are programmable (usually marked DIR/REV) which allows the controller to be switched from direct acting to reverse acting or vice versa.
It is important to get the correct direction of control action. If things are set-up correctly a feedback control system will experience negative feedback, which means that the system will act to reduce errors in its output.
If you get the direction of control action wrong the system will undergo positive feedback and will act to reinforce output errors – this is very likely to cause the system to go unstable. If you are having problems in setting up a stable controller the first thing to check is that you have set the correct direction of control action!
If a fail open control valve is paired with a direct acting controller we get the following process performance: On rising process level the controller output rises which closes the valve.
If the process level is below the set point the controller would be wide open.
This would behave similar to a direct acting regulator only the valve / controller response is slower.
In this case when the process level rises the controller output decreases which tends to open the valve.
If the process level is below the set point the valve is closed.
An example of this application is a compressor recycle valve.
This is the same as the fail open valve / reverse acting controller. An increase in process level means an increase in controller output which means the valve is opened.
If the process level is below the set point the valve is closed. A typical application is backpressure control. (In this case the valve controller acts similar to that of a PSV.)
A rise in process level means a decrease in controller output which means the valve is closed.
If the process level is below the set point the valve is open.
This is typically used for pressure control.
Post
An Article
A Blog
A News
A Video
An EBook
An Interview Question
Shrimant Telgave
Updated date Aug 12, 2019
62.8k
4
9
facebook
twitter
linkedIn
Reddit
WhatsApp
Email
Bookmark
Print
Other Artcile
Expand
Let us learn all about Controllers with examples in ASP.NET MVC 5, via this article.
In this article, you will learn the following points about Controllers in MVC 5.
In the previous article, we got an introduction to ASP.NET MVC. If you are new, visit the following link.
MVC stands for Model, View, and Controller. MVC separates the application into three components like Model, View, and Controller. We will learn Controller in detail. A controller is one of the important components of MVC.
A controller can contain an action and non-action method.
It is used to handle the user request coming from the browser.
It will check the request from the browser and identify the action method and return the respective view.
A controller is inherited from “ControllerBase” class which is inside the “System.Web.MVC” namespace.
While creating controller remember it always suffix as “Controller” keyword.
Default Controller is “HomeController” and “Index” is view.
Following are the steps to create ASP.NET MVC 5 application using Visual Studio 2017,
Open => Visual Studio 2017 and go to File >> New >> Click on Project as follow.
Select “ASP.NET Web Application” and provide a meaningful name like “MVCControllerDemo” and Click on “Ok” button.
Select the “Empty” template and check the “MVC” checkbox from “New Web Application” window as follow.
The default project structure will create as follows,
The following steps will help you to create a controller in ASP.NET MVC 5.
Go to solution explorer Right-click on “Controller” Folder >> Click on Add >> click on “Controller” as follow.
Select “MVC 5 Empty Controller” from the window and click on “Add” button.
Provide a meaningful name like “HomeController” and Click on "Add" button.
Sample code of Controller as follows,
How to check if the Controller is inherited from “ControllerBase” class which is inside the “System.Web.Mvc” namespace?
Right-click on "Controller" click on “Go to definition” as follow.
Step to create a controller with read/write action in MVC 5 as follow,
Go to solution explorer Right-click on “Controller” Folder >> Click on Add >> click on “Controller” as follow.
Select "MVC 5 Controller with read/write actions" from the window and click on “Add” button.
Provide a meaningful name like “ProductController” and Click on “Add” button as follow.
Default code is generated for "MVC 5 Controller with read/write actions" as follow,
Open any browser and enter the URL like “DomainName/ControllerName” as follows.
Open the Routeconfig.cs file default file as follows.
Change the controller name as "Product" controller instead of the “Home” controller inside the Routeconfig file as follow.
The default controller gets executed based on configuration setting which applied in RouteConfig.cs file. We have provided the “Product” controller as default controller in Routeconfig.cs file. After executing the application default “ProductController” get executed.
Following are diagrams which will help you to understand the flow of ASP.NET MVC Controller.
As per the above figure, the user enters the URL on the browser, the given request goes to the server and calls the routing, which will execute the appropriate controller. And based on the request the controller executes the appropriate controller action method. It will pass the request to the model if the model has a database related operation then it will perform some database-related operation and get back the result to the controller. After it's completed, this controller returns the response to the user.
Interview questions for freshers on the controller,
I hope you understand the concepts of the controller in asp.net MVC 5.
Next Recommended Reading
Controller in ASP.NET MVC
View Previous Comments
9
4
95 23.6k 1.6m 1 1 Reply
437 5.2k 977.1k 0
84 25.4k 1.8m 1 1 Reply
437 5.2k 977.1k 1
In this article, we will learn about controllers in ASP.NET MVC5 and their examples.
Shrimant Telgave is a Senior Software Developer having experience in Design, developing and maintaining large-scale applications. He has good experience in C#, ASP.NET, ASP.NET MVC, SQL Server, Web Services, WCF, Entity ... Read more
©2022 C# Corner. All contents are copyright of their authors.
More at rubyonrails.org:
More Ruby on Rails
Blog
Guides
API
Forum
Contribute on GitHub
Start Here
Getting Started with Rails
Models
Active Record Basics
Active Record Migrations
Active Record Validations
Active Record Callbacks
Active Record Associations
Active Record Query Interface
Views
Layouts and Rendering in Rails
Action View Form Helpers
Controllers
Action Controller Overview
Rails Routing from the Outside In
Other Components
Active Support Core Extensions
Action Mailer Basics
Active Job Basics
Active Storage Overview
Action Cable Overview
Webpacker
Extending Rails
Rails on Rack
Creating and Customizing Rails Generators & Templates
Contributions
Contributing to Ruby on Rails
API Documentation Guidelines
Guides Guidelines
Policies
Maintenance Policy
class ClientsController < ApplicationController
def new
end
end
Copy
def new
@client = Client . new
end
Copy
class ClientsController < ApplicationController
# This action uses query string parameters because it gets run
# by an HTTP GET request, but this does not make any difference
# to how the parameters are accessed. The URL for
# this action would look like this to list activated
# clients: /clients?status=activated
def index
if params [ :status ] == "activated"
@clients = Client . activated
else
@clients = Client . inactivated
end
end
# This action uses POST parameters. They are most likely coming
# from an HTML form that the user has submitted. The URL for
# this RESTful request will be "/clients", and the data will be
# sent as part of the request body.
def create
@client = Client . new ( params [ :client ])
if @client . save
redirect_to @client
else
# This line overrides the default rendering behavior, which
# would have been to render the "create" view.
render "new"
end
end
end
Copy
GET /clients?ids[]=1&ids[]=2&ids[]=3
Copy
Copy
{ "company" : { "name" : "acme" , "address" : "123 Carrot Street" } }
Copy
{ "name" : "acme" , "address" : "123 Carrot Street" }
Copy
{ name: "acme" , address: "123 Carrot Street" , company: { name: "acme" , address: "123 Carrot Street" } }
Copy
get '/clients/:status' , to: 'clients#index' , foo: 'bar'
Copy
class ApplicationController < ActionController :: Base
def default_url_options
{ locale: I18n . locale }
end
end
Copy
class PeopleController < ActionController :: Base
# This will raise an ActiveModel::ForbiddenAttributesError exception
# because it's using mass assignment without an explicit permit
# step.
def create
Person . create ( params [ :person ])
end
# This will pass with flying colors as long as there's a person key
# in the parameters, otherwise it'll raise an
# ActionController::ParameterMissing exception, which will get
# caught by ActionController::Base and turned into a 400 Bad
# Request error.
def update
person = current_account . people . find ( params [ :id ])
person . update! ( person_params )
redirect_to person
end
private
# Using a private method to encapsulate the permissible parameters
# is just a good pattern since you'll be able to reuse the same
# permit list between create and update. Also, you can specialize
# this method with per-user checking of permissible attributes.
def person_params
params . require ( :person ). permit ( :name , :age )
end
end
Copy
params . permit ( preferences: {})
Copy
params . require ( :log_entry ). permit!
Copy
params . permit ( :name , { emails: [] },
friends: [ :name ,
{ family: [ :name ], hobbies: [] }])
Copy
# using `fetch` you can supply a default and use
# the Strong Parameters API from there.
params . fetch ( :blog , {}). permit ( :title , :author )
Copy
# permit :id and :_destroy
params . require ( :author ). permit ( :name , books_attributes: [ :title , :id , :_destroy ])
Copy
# To permit the following data:
# {"book" => {"title" => "Some Book",
# "chapters_attributes" => { "1" => {"title" => "First Chapter"},
# "2" => {"title" => "Second Chapter"}}}}
params . require ( :book ). permit ( :title , chapters_attributes: [ :title ])
Copy
def product_params
params . require ( :product ). permit ( :name , data: {})
end
Copy
# Use the database for sessions instead of t
Le livreur entre dans la maison et me baise dans la buanderie
Latine plantureuse apprécie une grosse bite dans le cul
Brune excitée baisée en profondeur