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Trouble shooting and notification of OPC Client connection issues
by Rudy Poseika
    
    

The GEF Intellution OPC Client should recover when an OPC server it connects to is turned off or there is a connection issue.


As of June 1, 2004 – the most current OPC Client 'IO Driver' is:

Version 7.33 – Dated approximately February 9, 2004


Familiarity with GEF Intellution software is required for proper operation and maintenance of the software.

There is a read me file for the OPC Client driver that is included at the end of this document.

The highlights of the read me file include;


·         The OPC Client should be stopped before importing, reloading, or generating a process database.

·         If you shut down iFIX before shutting down the OPC Client Power Tool, you will not be able to restart iFIX. Shut down the OPC Client Power Tool before restarting iFIX.

       (Also see section D1).


Other notes, observations, tricks and tips:

  • Remember to look at the Configuration of the OPC Client Driver:

Menu OPTIONS, DEFAULT PATH, and Advanced tabs.

  • The default path should be set to the 'pdb' folder (if this is used with GEF Intellution

iFix).

  • The configuration file should be NODE.OPC (see read me file), where node = node

configured as per SCU. Also – stop SAC on start.

  • If you are initially doing database development in iFix, you can leave the Advanced Tab-

IO Server- Autocreate 'ON', but generally this should be turned 'OFF', since otherwise

data items in the tree can appear with no real connection to an OPC server.

  • ALWAYS try to optimize the poll configurations (if possible) for the data requests. The

OPC driver is different than other GEF Intellution IO drivers, but you can make different

groups, and ensure that the OPC feature for asynchronous communication is used (as

opposed to 'polling'.

(upgrading - do not forget to un-install previous version)

  • If you have UPGRADED from a previous version of the OPC Client Driver – it is

recommended NOT to use the original configuration file, but PRIOR to upgrading –

EXPORT the configuration (as CSV), and USE THIS CSV file to 'import' (open as..)

into the new version configuration.

  • Some customers have noticed that EXPORTING and IMPORTING in the same version can clear up issues if 'corruption' is suspected.

  • If the configuration or application is really suspected to be corrupt then the following

steps may be carried out:

Customer called indicating he can not connect to his OPC configuration (default.opc)

1.   Shut fix down

2.   Delete opc*.* from fix root dir.

3.   Delate *.opc from pdb dir.

4    Install (reinstall) the opc client**

  • During the install process – there may be a prompt regarding install server or client? =

Always install server also. The 'client' is the OPC client – the 'server' is that it is a server

to GEF Intellution (and also OPC clients).


DCOM is a most difficult issue to address in the world of OPC. That is when the OPC Client is on a DIFFERENT machine than the OPC server. The low maintenance, easy to solve method is to use new OPC technology from a variety of suppliers – called 'OPC Tunnels' or 'OPC bridges'. This is a piece of software that resides BOTH on the local PC of the OPC client, and on the remote OPC Server. These two pieces of software talk to each other, and the OPC client thinks it is talking to a local OPC server, though it is not.

The software solution involves standard http, (xml) and SOAP protocols to send data across, so DCOM is not an issue. There are several vendors in Europe and North America for this solution. CB Automation can help in the appropriate selection.


To tackle DCOM there are many documents and applications available to help. Trouble is there are many documents required. DCOM takes into account security settings of users and applications on both respective PCs, and sometimes if one property is changed (new security policy from IT and 'head office' automatically sent to all PCs) it can take hours to determine where the issue originates. The basic application for Windows NT etc is called DCOMCFG.


Also – there are parts of the server software that may need to be installed on the client side for the 'data name space' to be recognized. This would be documented with the OPC server. Some terms for this may be called 'opc proxy stubs'.


There is GEF Intellution KB article I020061 that is one source.”OPC, DCOM, and Security White Paper”

The applications have to be configured correctly, and if the OPC Client, maybe iFix, and the OPC Server on the other computer are started as 'Services' this adds another layer to the maintenance of the software environment.

To start the OPC Client Driver manually, use the green arrow in the toolbar. Select the Statistics button to verify communications. Bad data quality is usually the result of an incorrect Item ID syntax of if the particular item is not available. To verify general connectivity to the server, check the statistics at the server level in the OPC Client configuration tree to verify that the server is running.


There is a server log available to help look at the history of the OPC communications. This is accessed by way of the 'event window' This is a separate window, so look for this apart from the OPC client interface.

In order for the IO Driver (OPC Client) to have a chance to obtain data from the OPC server(s) it is talking to – it is recommended to put a delay on WSACTASK (upon iFix startup). This is documented in the iFix help ebooks.  WSACTASK.EXE D45, for example for a 45 second delay. In some applications I have seen this as high as 120.

If the OPC server is suspected as being corrupt – please check with that vendor. Sometimes 're-registering' the server will solve a problem, sometimes you may have to un-install and re-install (follow vendor recommendations).

Generally - also review with the OPC server vendor on the most recent version of the OPC server, to see if updates may address other issues.


For iFix users


GEF Intellution iFix has its own alarming system and sends 'messages' and notifications to the alarm locations. Only process alarms are sent to the Operator Interface, but messages from the OPC client can appear in other destinations. This may be helpful in determination of issues. If an automated warning is required, then a 'heartbeat' concept may be implemented – monitor an OPC data item and if there is no data, or the data 'flat lines' for a certain period of time.


Here is the README File for the OPC Client Driver from GE Fanuc Intellution:

***************************

Intellution iFIX OPC Client Version 7.33 Release Notes 09/24/03

Contents

A. Required Software

B. General Information

C. Known Issues

D. Troubleshooting

D.1 Automatically Starting the OPC Client

D.2 USING LICENSING SOFTWARE

A. REQUIRED SOFTWARE

The OPC Client driver requires the following software:

* Windows 2000 with Service Pack 2 or greater, Windows XP,

Windows NT 4.0 with Service Pack 5 or greater, or Windows Server 2003.

B. GENERAL INFORMATION

* The OPC Client should be stopped before importing, reloading, or

generating a process database.

* 7.x drivers no longer use the Period field in Mission Control.

* The OPC Client has an Overruns field in the Power Tool at the

driver, server, group, and item statistics level. You

can use this field as a troubleshooting tool to assist in

optimization. The presence of overruns do not necessarily

indicate a problem. Any of the following conditions can cause

overruns:

* Bandwidth saturation on your network.

* Turnaround delays in the PLC.

* Overflowing message queues in the process hardware.

Please refer to the OPC Client Help for more information on

overruns. You can find information on overruns by displaying

the driver statistics in the Power Tool, selecting the Overruns

field, and pressing the F1 key.

* Do not install or uninstall a new version of the OPC Client

while an old version is running. Always stop and exit the driver

before installing or uninstalling new version of the OPC Client.

C. KNOWN ISSUES

The OPC Client driver has the following known issues:

* Analog Register and Digital Register blocks in iFIX databases do not

support exception-based processing. In addition, the OPC Client does

not support using the Text block with exception-based processing.

* The OPC Client does not support exception-based processing for

database blocks that reference items configured as data arrays.

* Do not overlap data arrays when using RS-Linx v2.3 or greater. If you do

overlap arrays, modification of arrays element may change elements

that you do not intend to overwrite. Consequently, we recommend if

you require data arrays to overlap, use RS-Linx v2.2.

* If you shut down iFIX before shutting down the OPC Client Power Tool,

you will not be able to restart iFIX. Shut down the OPC Client

Power Tool before restarting iFIX.

D. TROUBLESHOOTING

Only use the OPC Client server window for troubleshooting.

When you are not debugging a problem, disable all debug messages and

close the server window. Leaving debug messages enabled or leaving

the OPC Client server window open degrades driver performance.

If you experience difficulty installing the OPC Client, refer to

the following sections for information on how to resolve the

problem.

D.1 AUTOMATICALLY STARTING THE OPC CLIENT

When you install the OPC Client, the installation program creates

a driver configuration file called nodename.OPC. FIX uses this

file when you automatically start the server. If you subsequently

change the name of your SCADA server after installing the OPC

server, FIX cannot automatically start the server because the name

of the node does not match the name of the configuration file. To

correct this, rename the configuration file to match the name of

your SCADA server. For example, if you change the name of the

SCADA server from SCADA1 to SCADA9, rename the configuration file

from SCADA1.OPC to SCADA9.OPC.

D.2 USING LICENSING SOFTWARE

You must use the latest Intellution Licensing software to avoid problems with key checking when the OPC Client launches an Intellution OPC Server. The Intellution Licensing software is available from the GE

Fanuc support web site at http://iglobalcare.gefanucautomation.com.

  
If Corruption is suspected...

Some customers have noticed that EXPORTING and IMPORTING in the same version can clear up issues if 'corruption' is suspected.   

DCOM ...

DCOM is a most difficult issue to address in the world of OPC.   

...to obtain data from the OPC server ...

It is recommended to put a delay on WSACTASK upon iFix startup.   

What is iSync?



   

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