Appendix A: Troubleshooting

The OPC UA service's log messages can be found in the main ACM Log Viewer window. Filter on the source asiOPC_UA.

Issue	Possible Reason or Solution
The Server’s application certificate is not in the certificate store	The asiOpcUa service must be started at least once to create the self-signed certificate
Could not connect to Server: BadCommunicationError	ACM asiOpcUa service is not running
Could not connect to Server: BadServerHalted	ACM asiData service is not running
Browse on node ‘ns=2;s=MyNodeId’ failed with error “BadNodeIdUnknown”.	Items in a browse list may not exist in the namespace at the time of browsing. Data Variable nodes are only created in the address space when a client creates a monitored item for it. However, monitored items can be created from any item in the browse list.
The server does not support the configured security policy ‘http://opcfoundation.org/UA/SecurityPolicy#None’.	A client cannot connect a session using security policy ‘None’ unless the configuration option “Accept Non-Secure Sessions” is enabled.
Clients cannot write to items in the DataAccess namespace.	Writes to items by Anonymous users are not allowed unless the configuration option “Allow Writes to Items by Anonymous Users” is enabled.
Error "BadSecurityChecksFailed" was returned during OpenSecureChannel.	The client is not a trusted application. Import the client's public key certificate file into the OPC UA server's trusted peer store.
RegisterServer2 failed for at: opc.tcp://localhost:4840/. Exception=Error establishing a connection: BadNotConnected	The OPC UA Server is trying to connect to the local OPC UA Discovery Service, which is not running. Start the Discovery Service if there is one installed. If not, edit the OPC UA Server settings and un-check the property option "Register with Local Discovery Service", then restart the OPC UA Server service.
Items in the client application fail to update. The client repeatedly sends Create Monitored Items requests to the Server for the same items.	The call to Create Monitored Items on the server cannot be completed within the timeout period set by the client application. Edit the OPC UA Server setting "Maximum Monitored Items per Call" and decrease the value by 100 (e.g. if the value was previously 900, set it to 800). Restart the OPC UA Service. Repeat this process if needed, lowering the number each time, until the problem no longer happens.

Log Messages

This partial list will document some of the OPC UA server's log messages that may occur in the ACM log viewer. A brief description of the message meaning is given. This may not be a complete list.

Log Message	Log Type	Detail
Failed to connect to asiData. Reason:	Error	The OPC UA server must connect to the ACM asiData service in order to create items and receive data updates. Verify the asiData service is running.
Disconnected from asiData	Error	The asiData service has stopped or the OPC UA server failed to connect to it.
Writes to items not allowed by anonymous users.	Error	Anonymous users cannot perform writes to nodes in the DataAccess namespace unless the configuration option “Allow Writes to Items by Anonymous Users” is enabled.
Attempting to start asiData.	Info	The configuration option "Only connect to asiData when there are active client sessions" is enabled and the server is attempting to start the asiData service.
Request to create X monitored items in session Y	Trace	A client has requested to create X number of monitored items in session with id Y
Incorrect namespace index. Item skipped:	Trace	A monitored item with a namespace index other than '2', the DataAccess namespace, is being requested by the client. This item is ignored by the DataAccess namespace and will be passed to the Server namespace for possible validation.
Adding item X to validation list	Trace	The first time a monitored item for a particular node is requested by the client, the server will validate the item name with the asiData service.
Expecting string type node ID for DataAccess namespace. Item skipped:	Trace	Monitored items in the DataAccess namespace must use a string type Node Id. Any other type is ignored and will be passed to the Server namespace for possible validation.
Requested item X exists in DataAccess address space	Trace	A monitored item is being requested by a client to a node that already exists in the DataAccess namespace. This is normal behavior if the client, or another client, had previously created a monitored item for the same node.
Item X is invalid, node not created	Trace	A monitored item with an invalid item name was requested by the client. The node for the item will not be created.
Creating object node:	Trace	A namespace node is being created that represents an ACM object
Creating variable node: X on parent Y	Trace	A namespace node is being created that represents an ACM item
Monitored item X created with Y monitoring mode.	Trace	Monitored item X is being created with a monitoring mode of Y as requested by the client
Monitored item X created with Disabled monitoring mode.	Trace	The client has requested to create monitored item X with a disabled monitoring mode
Node X monitoring mode changed to Y	Trace	The client has requested to change the monitoring mode on a monitored item
Monitored item removed from Node X, Session Y	Trace	The client has removed a monitored item from Node X
Request to Write to item X in session Y, Value: Z	Trace	The client has written a new value to a monitored item
Write result for item:	Trace	The write result to the ACM item as returned by the asiData service
Update for item A, Value: B, Quality: C, CH: D	Trace	The server has receive an item update from asiData for the item with Client Handle 'D'
Validating X items with ACM	Trace	The server is attempting to validate a list of item names with asiData
Adding X items to ACM	Trace	The server is attempting to create a list of new items with asiData
Added item A to Group B, CH: C, SH: D	Trace	The server successfully added an item to ACM with Client Handle 'C' and Server Handle 'D'
Removing item A from Group B, CH: C, SH: D	Trace	The server is attempting to remove item 'A', with Client Handle 'C' and Server Handle 'D', from ACM
Activate/Deactivate item A in Group B	Trace	The server is attempting to change the active state of an item in ACM