Networking OPC Data

The best way to network to remote OPC Servers is to install the OAS Service on the remote PCs where the OPC Server is running and use the built in network features of Open Automation Software that use WCF.

Easy Networking

How to network all products to central service using a fixed IP Address or registered domain name for the Internet.

If you decide you still want to use remote DCOM to connect to remote OPC Servers edit the file NetworkNodes.txt in C:Program Files (x86)Open Automation SoftwareOPC Systems.NET.

Remote OPC Servers

Connecting to Data Access OPC Servers is best implemented when the OAS Service is installed where the OPC Servers you are connecting to are. View Remote OAS Service Access on how to enable easy remote networking from the client applications to a service without using remote DCOM.

If you are having trouble connecting to a local or remote OPC Server try setting the Service Logon to a proper local User Account or use the OPC Data Fix which can be enabled using the OAS Service tray application.

OPC Server Identity

If you can obtain data from one OPC Client, but not other OPC Clients at the same time verify that the OPC Server identity is set to Interactive User in the DCOM Configurator. View the steps listed below.

If you are using the OPTO 22 OPC Server you will need to do this step after installing their OPC Server.

Step 1

Start the DCOM configurator by selecting run and type DCOMCNFG and select OK.

OPC Server Identity 542

Step 2

Select Component Services, Computers, My Computer, and DCOM Config.

OPC Server Identity 543

Step 3

Select the OPC Server you are connecting to in the right window and right click to select Properties.

OPC Server Identity 544

Step 4

Select the Identity tab and select the option “The interactive user.”

OPC Server Identity 545

Step 5

Restart the system and verify using the Task Manager under Processes that only one instance of the OPC Server runs with multiple clients connected to it.

DCOM Security Configuration

If both Open Automation Software and the OPC Foundation Sample Client are unable to access data from OPC Servers and the OPC Foundation Core components are installed use the following section to setup the DCOM Security of the operating system.


If it is not possible to edit limits in DCOM (buttons Edit Limits grayed, not like below):

DCOM Security Configuration 504

With regedit delete the 2 restrictions MachineAccessRestriction and MachineLaunchRestriction, in HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindows NTDCOM

DCOM Security Configuration 505

System Wide Configuration

dcomcnfg => System wide configuration

DCOM Security Configuration 506

My Computer => Properties

DCOM Security Configuration 507

DCOM Security Configuration 508

DCOM Security Configuration 509

DCOM Security Configuration 510

DCOM Security Configuration 511

DCOM Security Configuration 512

Access Permissions => Click Edit Default

DCOM Security Configuration 513

DCOM Security Configuration 514

DCOM Security Configuration 515

DCOM Security Configuration 516

Access Permissions => Click Edit Limits

DCOM Security Configuration 517

DCOM Security Configuration 518

DCOM Security Configuration 519

DCOM Security Configuration 520

DCOM Security Configuration 521

Performance… and Distribute COM…  same settings as ANONYMOUS

Launch and Activation Permissions => Click Edit Default…

DCOM Security Configuration 522

DCOM Security Configuration 523

DCOM Security Configuration 524

DCOM Security Configuration 525

DCOM Security Configuration 526

DCOM Security Configuration 527

Launch and Activation Permissions => Click Edit Limits…

DCOM Security Configuration 528

DCOM Security Configuration 529

DCOM Security Configuration 530

DCOM Security Configuration 531

DCOM Security Configuration 532

Performance… and Distributed COM…  same settings as INTERACTIVE

DCOM Security Configuration 533


If it is necessary to add a user click Add

DCOM Security Configuration 534

Click Advanced

DCOM Security Configuration 535

Click Find Now


OPC enum service DCOM configuration

DCOM Security Configuration 536

DCOM Security Configuration 537

DCOM Security Configuration 538

DCOM Security Configuration 539

DCOM Security Configuration 540

DCOM Security Configuration 541

RS-Linx OPC Server

The RS-Linx installation corrupts the OPC Foundation Core component and puts in an older version of the OPC Foundation Core components. Download them and reinstall them and restart the operating system if receive an RCW dll messing error.


If you are having trouble browsing RS-Linx go to Configure-Options-OPC and enable or disable the Classic RSLinx Fix for Browsing errors and select Apply Changes.

Also some versions of RS-Linx require you to select the + next to each branch first before selecting the branch to show the items.

OPC Data Fix

The OPC Data Fix is an easy solution to connect to OPC Servers that do not run as a Windows Service and require a Desktop Account permission to connect to the OPC Server. First verify with the OPC Foundation Sample Client if the OPC Server is working properly with Desktop account permission.

Step 1

Start the OAS Service control manager under the program group Open Automation Software.

OPC Data Fix 502

Step 2

Select the Enable OPC Data Fix button.

OPC Data Fix 503


OPC Foundation Sample Client

You can verify if the OPC Server is working correctly with the OPC Foundation Sample Client with the following steps.

If the value comes in from the OPC Foundation Sample Client by not Open Automation Software try enabling the OPC Data Fix using the OAS Service control manager.

Step 1

Start the OPC Foundation Sample Client under the program group Open Automation Software-Tools.

OPC Foundation Sample Client 501

Step 2

From the Server pull down list select Browse.

Getting Started-OPC Client 435

Step 3

Select the local OPC Server that you want to connect to.

If the OPC Server is now shown under Data Access 3.00 change the Specification to 2.XX.

Getting Started-OPC Client 436

Select the OK button when highlighted on the OPC Server.

Step 4

Create a group subscription by right clicking on the OPC Server and select Create Subscription.

Getting Started-OPC Client 437

Enter a Name for the subscription and select Next.

Getting Started-OPC Client 438

Step 5

Browse for the items you want to connect to.

Getting Started-OPC Client 439

Step 6

Double click on the items you want to monitor.

Getting Started-OPC Client 440

Step 7

Select Next and then Done and the value of the remote item will appear.

Getting Started-OPC Client 441

If the value comes in from the OPC Foundation Sample Client by not Open Automation Software try enabling the OPC Data Fix using the OAS Service control manager.

OPC Communications – Troubleshooting

View the appropriate sub section for resolving communication problems with OPC Servers.