Fix VNA readings

- Load VNA config (and calibration) from file.
  The *.znxml file has to be prepared in advance and saved on the VNA.
  It needs to set the VNA to CW mode and single sweep.
- Trigger single sweep and wait for it to complete
- Fix trace definitions

Python_script/VNA.py

@@ -196,6 +196,40 @@ class Vna:
         self.vna.write("SYST:PRES; *OPC?")
         self.vna.read()
 
+    #Hack: put in the frequency which is configured in the config file to guess if loading was
+    #successful. FIXME: Do proper error checking here
+    def load_config(self, config_file, frequency):
+        """
+        Load the config from the VNA's internal drive. It must be in the folder
+        C:\\Users\\Public\\Documents\\Rohde-Schwarz\\ZNA\\RecallSets\\
+
+        Parameters
+        ----------
+        config_file : str
+            znxml file with VNA config and calibration. Only the file name without folder.
+
+        """
+        
+        #Backslashes are escaped. Default path on the ZNA.
+        directory = 'C:\\Users\\Public\\Documents\\Rohde-Schwarz\\ZNA\\RecallSets\\'
+        full_path = directory+config_file
+        #The string has to have single quotes, so we use double quotes to define the string.
+        self.vna.write("MMEM:LOAD:STAT 1,'"+full_path+"'")
+        self.vna.query('*OPC?')
+
+        #FIXME: raise exception if loading not successful
+
+    def do_single_sweep(self):
+        """
+        Start a single sweep and wait until it is done.
+
+        Notice: Due to the hard coded timeout of 5 seconds, the sweep must not take longer!
+        """
+        #start measurement
+        self.vna.write('INIT1')
+        #wait until finished
+        self.vna.query('*OPC?')
+        
     def close(self):
         self.vna.close()
 

Python_script/VNA_dummy.py

@@ -116,9 +116,10 @@ class VnaDummy:
                 result.append(float(x))
         return result
 
+    def load_config(self, config_file, frequency):
+        pass
 
-
-
-
+    def do_single_sweep(self):
+        pass
 
 

Python_script/prototype.py

@@ -42,6 +42,7 @@ class Measurements:
         self.max_delta_phase = config_data['delta_phase']
         self.sleep_time = config_data["sleep_time"]
         self.frequency = config_data["frequency"]
+        self.vna_config_file = config_data["vna_config_file"]
         target_accuracy = [self.max_delta_temp, self.max_delta_hum]
         self.chamber = climate_chamber.create_chamber(chamber_address, target_accuracy)
         self.vna = VNA.create_vna(vna_address, target_accuracy)
@@ -54,16 +55,11 @@ class Measurements:
         self.magnitude_stable = False
         self.phase_stable = False
 
+        self.vna.load_config(self.vna_config_file, self.frequency)
         self.vna.create_new_trace("Trace1", "S11")
-        self.vna.create_new_trace("Trace2", "S11")
+        self.vna.create_new_trace("Trace2", "S12")
         self.vna.create_new_trace("Trace3", "S21")
-        self.vna.create_new_trace("Trace4", "S21")
-        self.vna.create_new_trace("Trace5", "A1")
-        self.vna.create_new_trace("Trace6", "B1")
-        self.vna.create_new_trace("Trace7", "A2")
-        self.vna.create_new_trace("Trace8", "B2")
-        self.vna.set_cw_frequency(self.frequency)
-        self.vna.set_sweep_mode('CW')
+        self.vna.create_new_trace("Trace4", "S22")
 
     def perform_measurements(self):
         with open(self.output, mode='w', newline='') as csv_file:
@@ -194,9 +190,10 @@ class Measurements:
         [temp, hum, mode, alarms] = self.chamber.read_monitor().split(',')
         power = self.vna.get_current_power()
         frequency = self.vna.get_current_cw_frequency()
+        self.vna.do_single_sweep()
         s11 = self.get_trace_data("Trace1")
-        s21 = self.get_trace_data("Trace2")
-        s12 = self.get_trace_data("Trace3")
+        s12 = self.get_trace_data("Trace2")
+        s21 = self.get_trace_data("Trace3")
         s22 = self.get_trace_data("Trace4")
 
         return MeasurementData(int(self.clock.time()), temp, hum, power, frequency, s11, s21, s12, s22)

Python_script/test_stand_parameter.json

-{"delta_temp": 1, "delta_hum": 2, "delta_mag": 0.1 , "delta_phase": 5, "sleep_time": 1.0, "frequency": 1300000000}
+{"delta_temp": 0.1, "delta_hum": 1, "delta_mag": 0.1 , "delta_phase": 0.02, "sleep_time": 1.0, "frequency": 1300000000, "vna_config_file": "climate-lab.znxml"}