The default value is 8000.
If, for example, the value of the property is set to 5000, then if the viewer has to display in its range of the time axis 7000 values, only 5000 oldest values are displayed.The value of this constant is also sent to the server that returns to the client no more values than there are set in this property.
The number of points sent by the server to the client is also influenced by setting the "Maximum point count returned in message by trend server (for one variable)" configurator.
If PointsMaxVisibleCount=-1, then the number of displayed points is limited by the maximum size of the buffer for the data and this is 60000.
var oTView = pMe.Items("../TrendView");
var nMaxVis = oTView.PointsMaxVisibleCount; //reading
oTView.PointsMaxVisibleCount = 10000; //writing