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.

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Step 2

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

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Step 3

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

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Step 4

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

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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.

Registry

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

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

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System Wide Configuration

dcomcnfg => System wide configuration

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My Computer => Properties

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Access Permissions => Click Edit Default

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Access Permissions => Click Edit Limits

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Performance… and Distribute COM…  same settings as ANONYMOUS

Launch and Activation Permissions => Click Edit Default…

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Launch and Activation Permissions => Click Edit Limits…

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Performance… and Distributed COM…  same settings as INTERACTIVE

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SYSTEM WIDE CONFIGURATION => ADD A USER IN COM security

If it is necessary to add a user click Add

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Click Advanced

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Click Find Now

COM APPLICATION WIDE CONFIGURATION

OPC enum service DCOM configuration

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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: http://www.opcsystems.com/OPC/Tools/OPCCoreComponentsRedistributable(x86).zip

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.

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Step 2

Select the Enable OPC Data Fix button.

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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.

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Step 2

From the Server pull down list select Browse.

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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.

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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.

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Enter a Name for the subscription and select Next.

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Step 5

Browse for the items you want to connect to.

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Step 6

Double click on the items you want to monitor.

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Step 7

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

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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.

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