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| Name | Description | Unit | Default value |
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OPC HDA: Server if Available | OPC HDA server name (ProgID), if it is available. OPC HDA functions not to be activate use empty text. | - | |
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OPC HDA: Max. Number of Values | Sets the parameter NumItems at synchronous reading of historical "raw" values. The implicit value 0 (zero) means all values in the given interval. | - | 0 |
| Starts the sequencing of calling the function Refresh2 of interfaces Async I/O 2.0 and Async I/O 3.0. The calling executes after the first calling has been finished (after it gets the values). | YES/NO | NO |
Repeat Failed Group Activation | Failed OPC group activations will be attempted again after a delay specified by parameter "Group reactivation delay". | YES/NO | YES |
| A delay after which a failed OPC group activations is repeated if repetition is enabled by parameter "Repeat failed group activation". | sec | 30 |
Reconnect After Failed Group Activation | When an OPC group activation fails, KOM disconnects from OPC server and reestablishes a connection. Parameter is relevant in a configuration of redundant OPC servers (after a disconnect from an OPC server follows a reconnect to alternate OPC server where group activation may be successful). | YES/NO | NO |
| Period of executing the call of GetGroupState of interface IOPCGroupStateMgt. This synchronous call is repeated periodically and detects the problems which could occur in communication with OPC Server. | sec | 10 |
Accept All GetGroupState Errors | All the errors returned by calling of "GetGroupState" of interface IOPCGroupStateMgt are considered to be fatal (they will result in disconnect from the OPC server and reconnect or in restart of the KOM process). An example of error message returned by "GetGroupState":
WARNING: Siemens.TXP.OPC caused COM/OPC error 80010108H on IOPCGroupStateMgt::GetState(), Error string : The object invoked has disconnected from its clients. | YES/NO | NO |
Stop KOM When OPC Server Fails | Allows to stop KOM process when the fatal error occurs in communication. See the Note. | YES/NO | NO |
| Only the active KOM process (i.e., the active instance connected to the HOT server) communicates with the OPC server. The KOM process, which becomes passive (by changing the active instance or switching the redundancy), closes the connection to the OPC server.
Note: This parameter allows to reduce the OPC server load in redundant D2000 systems as well as to solve roblems with license limitation of the number of OPC clients. | YES/NO | NO |
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- On the computer with OPC server use the command "dcomcnfg" to start "Component Services" (or start it in "Administrative Tools").
- Select "Properties" menu in "Component Services" -> "Computer" -> "My Computer".
- Make sure that DCOM is enabled, i.e. parameter "Enable Distributed COM on this computer" on "Default Properties" tab is checked.
- In the list of components (branch "DCOM Config" under "My Computer"), select required OPC server and open the dialog box containing its parameters (Properties). Click the Security tab.
- The parameter "Launch And Activation Permissions" set to Customize and click Edit... button.
- Find the required user and if is not in the list, add him/her into..
- Enable the options "Remote Launch" and "Remote Activation".
- The parameter Access permission set to Customize and click Edit... button.
- In the "Identity" tab check whether "The launching user" or "This user" option is enabled, which is also the checking of user account that you configure. Typically, we recommend the setting "The launching user". If some problems occur, try direct setting "This user". In any case, be careful about setting "The interactive user", which is absolutely not recommended! The OPC server can be accessible and started only if some user is interactively logged on to computer with OPC server. This setting leads to the problems such as unavailability of OPC server, e.g. after its starting until any user is logged on.
- If you must use the setting "The system account (services only)", i.e. OPC server works as Windows service, watch the level of access rights of "SYSTEM" according to above mentioned rules.
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there is necessary to add a user in context of whose the communication runs. In "Component Services" on the computer with OPC client (KOM process) add this user to the list of users on the "COM Security" tab -> "Edit Limits", for both the parameters "Access Permissions" and "Launch and Activation Permissions" and enable "Remote Access" / "Remote Activation". It is problem connected with the establishing the call-back connection with OPC server. In this case, the roles are reversed and OPC client (i.e. KOM process) works as DCOM server. Adding this user and enabling the remote access enables establishing the call-back procedures between OPC client and OPC server. Call-back procedures are necessary for acquiring the values from OPC server in the asynchronous mode "Async I/O 2.0" and "Async I/O 3.0".
| Info |
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| title | Note about SIMATIC NET OPC.SimaticNET and possibly other OPC servers |
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If the OPC server is configured to run under "The interactive user" on the last tab Identity of the "Properties" dialog window, it may cause the OPC server to be available only when a user is logged on the computer. We recommend to change this setting to "The launching user", "This user", resp. "The system account". |
| Info |
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| title | Another note about OPC.SimaticNET |
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In the specific case for the OPC communication to work, it was required: - DCOM setting of OPC server OPC.SimaticNET - option "This user" (e.g. D2000 user) had to be enabled in the Identity tab. If "The launching user" was enabled, the connection to the OPC server timeouted (both for D2000 KOM and Matricon OPC Explorer), although it could be seen in Task Manager that the OPC server (opcdaserver.exe) was started under the specified user.
- the specific user with whose credentials the OPC server was running (e.g. D2000 user) had to be in the "Distributed COM Users" and "Administrators" groups. If the user was not an administrator, KOM process reported an error CoCreateInstanceEx(CLSCTX_REMOTE_SERVER), Error string : Class not registered).
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Errors and problems
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