The value of the SeriesID property of the first TimeSeries passed into the method will be copied to the SeriesID property of the TimeSeries returned to the client. Client applications may make use of this to keep track of asynchronous calls to InsertPIData.
GetPISnapshotData would return the snapshot value of each path (a PI tag) passed to it. There is no time range involved.
When you ask about NumValue, what method are you referring to?
Thank you for your reply.
I'm referring to GetPIArchieveData. For this method, NumValue, in the PIArchManner, is 400 by default.
Use the NumValues property to specify how Archive values are retrieved:
- For interpolated values, NumValues sets the number of interpolation intervals into which the time range is evenly divided.
- For Plot Values, NumValues sets the number of screen pixels in the representation of a trend.
- For Compressed values, NumValues sets the maximum number of values to return.
Minimum value is 1. Default: 400.
In the first two cases, the higher NumValues the more values you are requesting from PI Server (heavier query). While in the last case, you would just cap the maximum number of events retrieved from PI Server.
The reason for the default value of 400 values maximum, is a simple protection. It is to protect the developer/integrator from inadvertently making exceptionally large queries (and potentially affecting other modules/applications). One needs to keep in mind this is a product designed to be used over distributed architectures, potentially the WAN, and different scalability/usability metrics must be taken into account in the design. In general I would kindly advise against just leaving out default values and 'hope they do the trick'; default values (especially for quantitative parameters, as opposed to boolean/flags) are meant to help start using a given function, after which one refines his use of it. They obviously cannot suit any and all use cases and system sizes.