1 Reply Latest reply on Jan 16, 2017 12:45 PM by gregor

    Using Python to Retrieve Sampled Data with PI SDK




      I have some 'Sampled Data' I would like to pull from a PI Server using Python + PI SDK. I am having trouble using InterpolatedValues2(Start_Time, End_Time, SampleInterval) to pull the values. I suspect the issue is with the SampleInterval argument. I get an error when I pass a time interval of "24h" in which states 'The python instance can not be converted to a COM object'. I am currently also using win32com. Anyone know how I can pass this is as a COM object string?


      I've included my code below for reference:


      import datetime as dt
      import win32com.client as w32lc
      import numpy as np
      def NODW_recorded_data(start_time, end_time, pi_tag):
          Fetches recorded data from the NODW PI server for a PI tag between the given dates
          :param start_time: a datetime object.
          :param end_time: a datetime object.
          :param pi_tag: a string
          :return: a numpy array with two columns. The first is the timestamp,
                   and the second is the recorded value.
          pisdk = w32lc.Dispatch('PISDK.PISDK')
          server = pisdk.Servers('SERVER1')
          con = w32lc.Dispatch('PISDKDlg.Connections')
          con.Login(server, '', '', 1, 0)
          pi_time_start = w32lc.Dispatch('PITimeServer.PITimeFormat')
          pi_time_start.InputString = start_time.strftime('%m-%d-%Y %H:%M:%S')
          pi_time_end = w32lc.Dispatch('PITimeServer.PITimeFormat')
          pi_time_end.InputString = end_time.strftime('%m-%d-%Y %H:%M:%S')
          point = server.PIPoints(pi_tag)
          recorded_values = point.Data.InterpolatedValues2(pi_time_start, pi_time_end, "24h")
          rows = int(recorded_values.Count)
          results = np.zeros((rows, 2), dtype='object')
          for i, sample in enumerate(recorded_values):
              results[i, :] = np.array([dt.datetime.fromtimestamp(int(sample.Timestamp)), sample.Value])
          return results


      Any help would be greatly appreciated.