Overview
Access types in Factory Studio define the specific methods for reading and writing values for each data point in a project, including polling rate, read on startup, and unsolicited input acceptance. The OnDisplayOrServer Access Type controls data read and write in the project and allows it only when certain conditions are met.
It is useful for projects with many communication points but not requiring constant data updates, reducing computational load, and improving performance. The OnDisplayOrServer Access Type works by checking two conditions, OnDisplay and OnServer, before permitting data read or write.
OnDisplay means data can be read or written only when the display containing it is open, while OnServer means data can be read or written when the project is running as an OPC server.
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Creating a New AccessType
To create or edit an AccessType:
- Go to Devices → AccessTypes.
- To edit an existing type, double-click a field and configure it as desired.
- To create a new type, click the New item... button.
Customizing The Pre-Defined AccessTypes
Our platform comes with several pre-defined access types that define the specific methods for reading and writing the values of each data point. To further optimize data exchange, users can customize these access types as needed. To customize pre-defined access types:
To configure access types:
Device AccessType Configuration Properties | |
|---|---|
Field/Column | Description |
Name | Enter a name for this access type. |
Read | |
ReadPolling | Select when you want to enable read polling. |
ReadPollingRate | Enter how often the address value is retrieved. |
ReadTrigger | Enter an object property that tells the system when to read the value. |
OnStartup | When selected, the system reads the value on startup. |
Write | |
WriteEvents | Select to enable the writing of values to the PLC. |
WriteEvent | Select when the value is written. |
WriteTrigger | Enter an object property that tells the system when to write the value. |
Settings | |
AcceptUnsolicited | When selected, the system accepts values from the PLC, even if the polling time has not yet elapsed. |
UseStaticBlocks | Select to use the block command field |
BlockCommand | Enter a definition for each block that will be created. Check the driver documentation to see if the specific driver uses this field and the valid values. |
Description | Enter a description for the access type. |
One very efficient AcceesType is to only read data when it is being used by the application.
Configuring AccessType as OnDisplayOrServer
On the dialog window, you need to configure the ReadEnable field to OnDisplayOrServer.
This property is enough for the Reading portion of the communication. You can also enable Writing Events by selection the WriteEventEnable checkbox.
The OnDisplayOrServer Access Type is a great tool for projects that have a large amount of Communication Points but do not require the data to be constantly updated for all of them.
It can help computers that lack computational power to handle a huge volume of data exchange while also maintaining other modules (Scripts, Alarms, etc) at the same time.
In these situations, an OnDisplayOrServer Access Type can be beneficial to the Project's performance.
The OnDisplayOrServer Access Type operation process can be divided into two aspects:
- OnDisplay
- OnServer
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ONLY when and while ANY of these options are met, the Communication Points with this AccessType can Read/Write data. |
On Display
The OnDisplay part means that your Communication Point will only begin Reading/Writing when the Project display that contains these tags is actually open.
To illustrate, let us say we have a project with two displays: one for LineA and the other for LineB; Each display has its own specific Tags added to it (Tag.LineAProduct1..., Tag.LineBProduct1...)
When the Project is running, there is no need to send/receive data for all Tags in the PLC. The Project only needs to send/receive data for the ones that are in the display that is currently opened on the Visualizer.
So, when LineA display is open, only LineA tags will communicate. The same goes for LineB.
Or Server
The OrServer or OPCServer means that if your Project is running as an OPC Server the AccessType will behave as if its ReadEnable property is set to Always.
If you have the tags on the server-side as Script Tasks, Classes, Expression, Alarm Items, etc. You need to create a new AccessType specific for them with the ReadEnable option in Always.
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