2) Citect OPC Tag Browse "Invalid class string" error.

When attempting to browse remote OPC servers from a separate PC on the same network, I get the error "Invalid class string" when I press "Connect" on the OPC Data Access Parameters dialog box. The cause of this problem is the incorrect registration of the OPC binaries opcenum.exe, opccomn_ps.dll and opcproxy.dll. This happens for example we have installed and uninstalled different OPC servers and clients from different companies, and their instalation scripts do different things.

Citect uses:

(OPC Tag Browser)opcenum.exe - to detect Data Access OPC servers in the local and remote machine.

opccomn_ps.dll - OPC Foundation Common Interfaces 1.0 Proxy

opcproxy.dll - OPC Foundation Data Access 2.0 Proxy

Solution:

Unregister them:

opcenum /unregserver
regsvr32 opccomn_ps.dll /u
regsvr32 opcproxy.dll /u

Then register:

opcenum /regserver
regsvr32 opccomn_ps.dll
regsvr32 opcproxy.dll

3) Citect OPC Tag Browse "Class not registered" error.

When attempting to browse remote OPC servers from a separate PC on the same network, I get the error "Class not registered" when I press "Connect" on the OPC Data Access Parameters dialog box.

The cause of this problem is that our client PC does not have the necessary Prog ID of at least one of the Data Access OPC servers on the remote PC we want to connect to. The client PC needs to have the Prog IDs of ALL Data Access OPC servers.

Solution:

The simplest solution is to install the "Client Install" version of the OPC server software on the client machine. This option installs only the necessary Prog IDs required. If the OPC Server does not have a client install option, you have to manually do this procedure to the system's registry:

Note:

This method may not work for every OPC client. Please check the client documentation for more information.

1. On the remote machine where the OPC server is installed, run REGEDIT as a user that has access rights to the local registry.

2. Expand the HKEY_CLASSES_ROOT key.

3. Find the program ID(s) for the desired OPC server(s).

In the case of Matrikon OPC Servers, the ID has the form Matrikon.OPC.Device. If you quickly type the first few letters or the ID, the REGEDIT program should jump to the location of that key. Some servers may have both a version-specific as well as a version-independent program ID. In this case both ID's should be copied to the client machine.

4. For each program ID, select the key and choose Export Registry File from the Registry menu. Enter a file name, and then click Save. Be careful not to overwrite other export files that you are creating.

5. Copy the exported REG files to the client machine.

6. Merge the REG files into the registry of the client machine. This should simply be a matter of double clicking on the file from the desktop of the clientmachine. Alternatively, run REGEDIT on the client machine and choose Import Registry File from the Registry menu, selecting each file in turn. This must be done as a user who has write access to the local registry.

7. Use REGEDIT to check that the program IDs have in fact been copied. Delete the REG files since they are no longer needed.

4) Citect OPC Tag Browse no error but does not display any local OPC server.

When attempting to browse remote OPC servers from a separate PC on the same network, I get no errors but there are no OPC Servers detected when I press "Connect" on the OPC Data Access Parameters dialog box.

Solution:

Same as Problem "Citect OPC Tag Browse "Invalid class string" error" above.

5) Citect OPC Tag Browse "The RPC server is unavailable".

When attempting to browse remote OPC servers from a separate PC on the same network, I get the error "The RPC server is unavailable" when I press "Connect" on the OPC Data Access Parameters dialog box.

Solution:

The machine name is not recognized by the system, please check the machine name in the network and do the connection again.

Citect has confirmed these to be a problem in CitectHMI/SCADA version 5.50 We are researching this problem and will post new information here as it becomes available.