OPC UA Server Advanced Settings
In most circumstances, you will not need to modify any of the advanced UA server settings. Anyhow, if you do need to change or tweak some of these, they can be modified directly in the UAServer sub-key of the Windows registry key of the Hive instance.
The set of advanced UA server settings are described in the following table:
| Name | Description | Default value | Require restart to apply |
|---|---|---|---|
| Enabled | Not in use, will be removed in a future Apis version | 0 (false) | Yes |
| Enable_DownSampling | If enabled, VQTs with timestamp delta less than the sampling interval is dropped | 0 (false) | Yes |
| EngineeringUnits_UnitAttributeFallback | If enabled, use proprietary EUInformation when proper EUInfo is unavailable | 0 (false) | Yes |
| ForceAllowHistoryWrite | If enabled, allow HistoryWrite on any node 1 | 0 (false) | No |
| Limits_JobWorkers | Not in use, will be removed in a future Apis version | 0 (false) | Yes |
| Limits_MaxArrayLen | Specifies max items per Publish response | 0x1000000 | Yes |
| Limits_MaxEventQueue | Specifies max queuesize on event subscriptions | 0x100000 | Yes |
| Limits_MaxHistoryRead_Events | Specifies max number of events per HistoryRead | 0x2000 | Yes |
| Limits_MaxHistoryRead_VQTS | Specifies max number of VQTs per HistoryRead | 0x10000 | Yes |
| Limits_MaxJobs | Not in use, will be removed in a future Apis version | 0x100 | Yes |
| Limits_MaxSamplingFuzz | Fuzzy deltatime limit when downsampling is enabled, in milliseconds | 0x10 | Yes |
| Limits_MaxSubscriptionsPerSession | Max number of subscriptions per session 2 | 0 | Yes |
| Limits_MinSamplingInterval | Min samplinginterval accepted by the server, in milliseconds | 10 | Yes |
| MaxThreadsPerCore | Max number of threads per core for parallelized HistoryRead processing | 8 | Yes |
| NS2 | Static URI to use for namespace 2 (Apis Hive canonical namespace) | Yes | |
| NsTable | Static initial set of semicolon-separated URIs in the servers namespace table | Yes | |
| Parallel_ClientSamplers_Threshold | Control if/when to parallelize Event broker commands 3 | 1000 | No |
| Persist_NsTable | If enabled, the active namespace table is saved into NsTable at shutdown | 0 | Yes |
| PKI_* | Settings related to security/use of certificate 4 | ||
| RedundancySupport | The type of redundancy reported by the OPCUA server 5 | 0 | Yes |
| Root | Not in use, will be removed in a future Apis version | Yes |
1 When set to 1, the HistoryWrite AccessLevelType on the target node is ignored
2 When set to 0, use the default limit in the Apis OPCUA Server SDK, which is 1024 as of Apis 9.16
3 The Event Broker commands UaServerSampleMonitoredItems and UaServerUpdateMonitoredItems_DataPush will be executed in parallel when the number of active OPCUA subscriptions passes this limit
4 Use Certificate Management in Apis Management Studio to configure these settings
5 Use the Property Editor in Apis Management Studio on your Apis Hive instance to configure these settings