Troubleshooting – OPC DA

Troubleshoot Bad Data

How to identify and resolve communications errors with data sources.

  • 0:00 - Introduction
  • 0:40 - Bad Tags
  • 3:30 - System Errors
  • 4:20 - Watch Window
  • 6:20 - Error Logging
  • 7:20 - Troubleshooting Guides
  • 8:55 - Contact Us

I am unable to browse and OPC Server or get good data quality for the OPC Items?

View the OPC Communications - Troubleshooting section in this file on how to resolve all OPC Server communication errors.

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. 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 use the Configure-OAS application and go to Configure-Options-Networking to define the available IP addresses of the remote OPC server nodes in the Network Nodes list.
Configure Options
Networking Nodes
You will then be able to browse the remote systems under the Network Nodes with browsing for OPC servers. Network OPC Browse
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 Getting Started - Networking on how to enable easy remote networking from the client applications to a service without using remote DCOM.
If you prefer to use remote DCOM without OAS networking view Networking OPC Data troubleshooting topic on how to define the IP Address of remote systems under Configure-Options-Networking.
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 Services control 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
OPC Server Does Not Run as a Service
If the OPC server does not run as a Windows Service and OAS cannot connect to the server or is receiving bad data quality due to DCOM security permissions implement the OPC Data Fix or set the OAS Data Service LogOn to a local user account.
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.
Download: 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 Services control manager under the program group Open Automation Software. OAS Services Shortcut

Step 2

Select the Enable OPC Data Fix button. OPC Data Fix Enable
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.

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.
Getting Started-OPC Client 436
If the OPC Server is now shown under Data Access 3.00 change the Specification to 2.XX.
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.
RCW DLL Missing
If you receive an error that a RCW component is missing while browsing or connecting to any OPC Server install the OPC Foundation Core Components and restart the system. You can download the OPC Foundation Core Components from:
Overview - Troubleshooting OPC Communications
View the appropriate sub section for resolving communication problems with OPC Servers.
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