diff --git a/dev/test_2_mux_2024.py b/dev/test_2_mux_2024.py
index e3b168d4ebf2d6eba1faef9d90d0952ab7501002..5fb256f2a216cc936b54273ecc37e19c424d6321 100644
--- a/dev/test_2_mux_2024.py
+++ b/dev/test_2_mux_2024.py
@@ -52,7 +52,7 @@ if within_ohmpi:
     k._hw.switch_mux([1, 4, 2, 3], state='on')
     k._hw.vab_square_wave(12,1)
     k._hw.switch_mux([1, 4, 2, 3], state='off')
-    print(f'Resistance: {k._hw.last_rho :.2f} ohm, dev. {k._hw.last_dev:.2f} %, rx bias: {k._hw.rx._bias:.2f} ohm')
+    print(f'Resistance: {k._hw.last_rho :.2f} ohm, dev. {k._hw.last_dev:.2f} %, rx bias: {k._hw.rx._bias:.2f} mV')
     k._hw._plot_readings()
     plot_exec_log('ohmpi/logs/exec.log')
 change_config('../configs/config_default.py', verbose=False)
\ No newline at end of file
diff --git a/ohmpi/hardware_components/ohmpi_card_3_15.py b/ohmpi/hardware_components/ohmpi_card_3_15.py
index c901338fd8186dc31806ca4de6e6ddee2e724d4f..5043eb7ea2c6299fc433d54ab92e8778f6e0df90 100644
--- a/ohmpi/hardware_components/ohmpi_card_3_15.py
+++ b/ohmpi/hardware_components/ohmpi_card_3_15.py
@@ -254,6 +254,6 @@ class Rx(RxAbstract):
         """ Gets the voltage VMN in Volts
         """
         self.exec_logger.event(f'{self.board_name}\trx_voltage\tbegin\t{datetime.datetime.utcnow()}')
-        u = AnalogIn(self._ads_voltage, ads.P0, ads.P1).voltage * self._coef_p2 * 1000. - self._bias  # TODO:  check if it should be negated
+        u = -AnalogIn(self._ads_voltage, ads.P0, ads.P1).voltage * self._coef_p2 * 1000. - self._bias  # TODO:  check if it should be negated
         self.exec_logger.event(f'{self.board_name}\trx_voltage\tend\t{datetime.datetime.utcnow()}')
         return u
diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index 00054d0c1f040e53787f3ea5ae5734cf4056613a..b2740b5e9b8f361a9547fc6fc6ff4ed2aedde759 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -202,7 +202,7 @@ class OhmPiHardware:
     @property
     def last_rho(self):
         if len(self.readings) > 1:
-            return np.mean(self.readings[:, 2] * self.readings[:, 4] / self.readings[:, 3])
+            return np.mean(np.abs(self.readings[:, 4]) / self.readings[:, 3])
         else:
             return np.nan