hi ，all
deltav trend cannot show trend curve？where possiblely is a problem？i wait for any idea.
Leo, I am assuming you are using Process History View (PHV) to view your trends. PHV allows you to view and trend any parameter in DeltaV. It also searches the Continuous Historian to see if the parameter specified also has history. If so, you get an immediate hitorical trend displayed. If the parameter is not historised, then PHV will builed a trend for that parameter in real time.
So you first need to make sure the PHV client is pointed to the Historian. If it is not, you will only see current data, and the PHV trend will clear when you close the application, or refresh the trends.
Next, make sure the tag you are looking at is actually the tag historised. By default, DeltaV templates historise say the PID1/PV parameter. If you are asking for the AI1/OUT value in the trend, that parameter my not be in the historian and so you will get a current value.
PHV plots current values from its local OPC connection to DeltaV and will always draw a trend over time of this data. Historical data is collected independently and will automatically be called by PHV to fill in the history based on the trend time span. You must have history data defined and the PHV application must be directed to the appropriate Historical server to see history trends.
Andre Dicaire
In reply to Andre Dicaire:
In History Collection/General tab verify "Sampling period" and "Display Representation";
In History Collection/Advanced tab verify "Data Compression";
In Process History View/Parameter Reference verify "Plot method"
thanks,Andre.I really use PHV to view my trends.It recently don't show trends.It happened some days ago.could you have any way to solve?
In reply to Roman Kostuniak:
thanks .Roman.I will have a check.because I not stay in the work field.