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Devices → Tutorial | Concept | How-to Guide | Reference

Creating

To create and configure an AccessType, follow these steps:

1. Access Devices → AccessTypes.
2. Click on the plus icon.
3. Fill all the property fields with your desired configuration (see the table below for more details about each option).
4. Click Ok.

AccessTypes Properties

The following table describes each configuration property when creating an AccessType:

Field

Description

Name

Name of this AccessType.

Read

ReadPolling

Enables read polling.

ReadPollingRate

Defines 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

Enables the writing of values to the PLC.

WriteEvent

Defines when is the value written.

WriteTrigger

Enter an object property that tells the system when to write the value.

Settings

AcceptUnsolicited

If enabled, the system accepts values from the PLC, even if the polling time has not yet elapsed.

UseStaticBlocks

Enables the use of the block command field.

BlockCommand

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

Description of the access type.

OnDisplayOrServer setting

The OnDisplayOrServer AccessType is an excellent tool for solutions with many communication points but only requires data updates for some of them. It can help computers without the computational power to handle massive data exchange while maintaining other modules active. The OnDisplayOrServer operation process is divided into two aspects:

• On Display: On Display means that your DevicePoint will only begin reading or writing when the solution's display containing these tags is open.
  • Let us imagine a project with two displays, one for Line A and another for Line B. Each display has its specific Tags added to it. When the Project is running, there is no need to send or receive data for all tags in the PLC. The solution only needs to send or receive data for the opened displays of the visualizer. So, when the Line A display is open, only Line A tags will communicate. The same goes for LineB.
• On Server: On Server or OPCServer means that if your solution runs as an OPC Server, the Access Type will behave as if its Read Enable property is set to Always. 
  • Suppose you have the tags on the server side as ScriptTasks, Classes, Expression, or AlarmItems. In that case, you must create a new AccessType specific for them with the Read Enable option in Always.

Configuring an AccessType as OnDisplayOrServer

To configure an Access type as On Display Or Server, follow these steps:

AccessTypes

1. Navigate to Devices → AccessTypes
2. Click Plus icon
3. Configure properties
4. Click OK

AccessType Properties

Read Configuration

Write Configuration

Advanced Settings

Common AccessType Patterns

Continuous Monitoring

Name: AlwaysRead
ReadPolling: Always
ReadPollingRate: 1000
WriteEvents: False
OnStartup: True

Control Points

Name: ReadWrite
ReadPolling: Always
ReadPollingRate: 500
WriteEvents: True
WriteEvent: OnChange

Event-Driven

Name: Triggered
ReadPolling: Never
ReadTrigger: @Tag.ReadNow
WriteEvents: True
WriteTrigger: @Tag.WriteNow

OnDisplayOrServer Mode

Optimizes communication by activating points only when needed.

How It Works

OnDisplay Behavior:

• Points activate when display opens
• Deactivate when display closes
• Reduces unnecessary communication
• Improves system performance

OnServer Behavior:

• Always active when OPC Server running
• Required for server-side logic
• Scripts, alarms, expressions need this

Configuration

1. Set ReadPolling to OnDisplayOrServer
2. Configure ReadPollingRate
3. Enable WriteEvents if needed
4. Assign to relevant points

Use Cases

Display-Driven:

Line A Display → Line A Tags Active
Line B Display → Line B Tags Active
No Display → No Communication

Server Requirements:

• Script Tasks
• Class Methods
• Expressions
• Alarm Conditions

<ac:structured-macro ac:name="info"> ac:rich-text-body Server-side tags (used in scripts, alarms, expressions) require an AccessType with ReadPolling set to "Always" or a separate AccessType for OnDisplayOrServer mode. </ac:rich-text-body> </ac:structured-macro>

Trigger-Based Operations

Read Triggers

csharp

// Trigger read when button pressed
ReadTrigger: @Tag.RefreshButton

// Periodic trigger
ReadTrigger: @Tag.Timer.SecondTick

// Conditional trigger
ReadTrigger: @Tag.ProductionActive && @Tag.ShiftRunning

Write Triggers

csharp

// Write on command
WriteTrigger: @Tag.SendCommand

// Batch write
WriteTrigger: @Tag.BatchReady

// Conditional write
WriteTrigger: @Tag.Value > 100

Performance Optimization

Polling Rate Guidelines

Block Commands

For protocols supporting block transfers:

UseStaticBlocks: True
BlockCommand: "READ_BLOCK:100:50"

Benefits:

• Reduced overhead
• Faster updates
• Lower network traffic
• Improved efficiency

Check driver documentation for supported commands.

Best Practices Checklist

•  Group Similar Points - Same polling requirements
•  Use OnDisplayOrServer - For HMI-only data
•  Minimize Always Polling - Only critical points
•  Set Appropriate Rates - Match process dynamics
•  Use Triggers Wisely - Reduce continuous polling
•  Configure Startup Reads - Initialize important values
•  Test Performance - Monitor CPU and network load

Troubleshooting

Points not updating:

• Verify ReadPolling enabled
• Check polling rate
• Confirm display open (OnDisplay)
• Review trigger conditions

Write failures:

• Confirm WriteEvents enabled
• Check WriteEvent setting
• Verify trigger firing
• Review point access rights

Performance issues:

• Reduce polling rates
• Use OnDisplayOrServer
• Implement triggers
• Enable block commands

OnDisplay not working:

• Verify display contains tags
• Check AccessType assignment
• Confirm display runtime active
• Review server-side usage

Examples by Industry

Manufacturing

HMI Points: OnDisplayOrServer, 500ms
Alarms: Always, 250ms
Reports: Triggered, OnDemand

Building Automation

HVAC: Always, 5000ms
Lighting: OnDisplayOrServer, 1000ms
Energy: Always, 60000ms

Process Control

Critical: Always, 100ms
Process: Always, 1000ms
Historical: Triggered, 5000ms

In this section...

1. Access Devices → AccessTypes.
2. Click on the plus icon.
3. On the ReadPolling property, choose OnDisplayOrServer. This property is enough for the Reading portion of the communication.
4. Check the WriteEvents box to Enable Writing Events.

In this section: