Overview
Access types define the specific methods for reading and writing values for each data point in a solution, including polling rate, read on startup, and unsolicited input acceptance. The OnDisplayOrServer Access Type controls the data read and write permissions.
It is useful for projects with many communication points but not requiring constant data updates, reducing computational load, and improving performance. The On Display Or Server Access Type works by checking two conditions, On Display and On Server, before permitting data read or write.
On Display 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 An Access Types
To create and configure an Access Type, follow these steps:
- Access Devices → Access Types.
- Click on the plus icon.
- Fill all the property fields with you desired configuration (see the table below for more details about each option).
- Click Ok.
The following table describes each configuration property when creating an Access Type.
Field | Description |
|---|---|
Name | Enter a name for this access type. |
Read | |
Read Polling | Select when you want to enable read polling. |
Read Polling Rate | Enter how often the address value is retrieved. |
Read Trigger | Enter an object property that tells the system when to read the value. |
On Startup | When selected, the system reads the value on startup. |
Write | |
Write Events | Select to enable the writing of values to the PLC. |
Write Event | Select when the value is written. |
WriteTrigger | Enter an object property that tells the system when to write the value. |
Settings | |
Accept Unsolicited | When selected, the system accepts values from the PLC, even if the polling time has not yet elapsed. |
Use Static Blocks | Select to use the block command field |
Block Command | 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. |
On Display Or Server Acces Types
The On Display Or Server 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.
The On Display Or Server Access Type operation process can be divided into two aspects:
- On Display: The On Display part means that your Communication Point will only begin Reading/Writing when the Project display containing these tags is open. To illustrate, let us say we have a project with two displays: one for Line A and the other for Line B. Each display has its specific Tags added to it (Tag.LineAProduct1..., Tag.LineBP roduct1...)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 in the display currently opened on the Visualizer. So, when the LineA display is open, only LineA tags will communicate. The same goes for LineB.
- On Server: The OrServer or OPCServer means that if your Project runs as an OPC Server, the AccessType will behave as if its ReadEnable property is set to Always. Suppose you have the tags on the server side as Script Tasks, Classes, Expression, or Alarm Items. In that case, you must create a new AccessType specific for them with the ReadEnable option in Always.
Configuring The Acces Type as On Display Or Server
To configure an Access type as On Display Or Server, follow these steps
- Access Devices → Access Types.
- Click on the plus icon.
- On the Read Polling property, choose On Display Or Server. This property is enough for the Reading portion of the communication.
- To Enable Writing Events, check the Write Events box.
ONLY when and while ANY of these options are met, the Communication Points with this Access Type can Read/Write data.
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