diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index a4d1a9e6836f00d973ff4de8858f3fa05892de12..03a5e220d19ec4efb8967026853e600c25a0bd81 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -587,6 +587,7 @@ class OhmPiHardware:
         """
         self.exec_logger.event(f'OhmPiHardware\tvab_square_wave\tbegin\t{datetime.datetime.utcnow()}')
         switch_pwr_off, switch_tx_pwr_off = False, False
+        # switches tx pwr on if needed (relays switching dps on and off)
         if self.pwr_state == 'off':
             self.pwr_state = 'on'
             switch_tx_pwr_off = True
@@ -623,6 +624,9 @@ class OhmPiHardware:
                 self.tx.voltage = vab
         else:
             vab = self.tx.voltage
+
+        # switches dps pwr on if needed
+        switch_pwr_off = False
         if self.tx.pwr.pwr_state == 'off':
             self.tx.pwr.pwr_state = 'on'
             switch_pwr_off = True
@@ -638,6 +642,8 @@ class OhmPiHardware:
             self.tx.pwr.pwr_state = 'off'
     def _vab_pulses(self, vab, durations, sampling_rate, polarities=None, append=False):
         switch_pwr_off, switch_tx_pwr_off = False, False
+
+        # switches tx pwr on if needed (relays switching dps on and off)
         if self.pwr_state == 'off':
             self.pwr_state = 'on'
             switch_pwr_off = True
@@ -647,9 +653,12 @@ class OhmPiHardware:
             self.tx.voltage = vab
         else:
             vab = self.tx.voltage
+
+        # switches dps pwr on if needed
         if self.tx.pwr.pwr_state == 'off':
             self.tx.pwr.pwr_state = 'on'
             switch_pwr_off = True
+
         if sampling_rate is None:
             sampling_rate = RX_CONFIG['sampling_rate']
         if polarities is not None:
diff --git a/ohmpi/ohmpi.py b/ohmpi/ohmpi.py
index bd66fe3f18733acf64d3f06eec9b215ab77c9f87..c25164ea28c6f66449f7c5e052b8251cc4e266d4 100644
--- a/ohmpi/ohmpi.py
+++ b/ohmpi/ohmpi.py
@@ -822,7 +822,7 @@ class OhmPi(object):
         if self._hw.pwr.pwr_state == 'off':
             self._hw.pwr.pwr_state = 'on'
             switch_pwr_off = True
-            
+
         # measure all quad of the RS sequence
         for i in range(0, quads.shape[0]):
             quad = quads[i, :]  # quadrupole