diff --git a/ohmpi/hardware_components/mb_2023_0_X.py b/ohmpi/hardware_components/mb_2023_0_X.py
index 66d295e27b727b353682d9d43d659a03cbb36061..1f5efa983abd5fdf57aff38990a173d72650baf9 100644
--- a/ohmpi/hardware_components/mb_2023_0_X.py
+++ b/ohmpi/hardware_components/mb_2023_0_X.py
@@ -24,7 +24,9 @@ from ohmpi.utils import enforce_specs
 SPECS = {'rx': {'sampling_rate': {'min': 2., 'default': 10., 'max': 100.},
                 'data_rate': {'default': 860.},
                 'bias':  {'min': -5000., 'default': 0., 'max': 5000.},
-                'coef_p2': {'default': 2.50}},
+                'coef_p2': {'default': 2.50},
+                'voltage_min': {'default': 10.0},
+                },
          'tx': {'adc_voltage_min': {'default': 10.},
                 'adc_voltage_max': {'default': 4500.},
                 'voltage_max': {'min': 0., 'default': 12., 'max': 12.},
diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index 31b3e99866b86a774840f65728cc9a20ed1c7a45..95eaad9afc5fd7bcc26ff9ee199dc7474bfc11c8 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -33,9 +33,14 @@ for k, v in tx_module.SPECS['tx'].items():
     try:
         TX_CONFIG.update({k: TX_CONFIG.pop(k, v['default'])})
     except:
-        print(k, v)
+        print(f'Cannot set value {v} in TX_CONFIG[{k}]')
 
 RX_CONFIG = HARDWARE_CONFIG['rx']
+for k, v in rx_module.SPECS['rx'].items():
+    try:
+        RX_CONFIG.update({k: RX_CONFIG.pop(k, v['default'])})
+    except:
+        print(f'Cannot set value {v} in RX_CONFIG[{k}]')
 
 current_max = np.min([TX_CONFIG['voltage_max']/50/TX_CONFIG['r_shunt'], np.min([MUX_CONFIG[i].pop('current_max', np.inf) for i in MUX_CONFIG.keys()])])
 voltage_max = np.min([TX_CONFIG['voltage_max'], np.min([MUX_CONFIG[i].pop('voltage_max', np.inf) for i in MUX_CONFIG.keys()])])
@@ -145,14 +150,14 @@ class OhmPiHardware:
         self._start_time = None
         self._pulse = 0
 
-    def _gain_auto(self, polarities=[1, -1]):  # TODO: improve _gain_auto
+    def _gain_auto(self, polarities=(1, -1)):  # TODO: improve _gain_auto
         self.exec_logger.event(f'OhmPiHardware\ttx_rx_gain_auto\tbegin\t{datetime.datetime.utcnow()}')
         self.tx_sync.wait()
         current, voltage = 0., 0.
         for pol in polarities:
             self.tx.polarity = pol
             # set gains automatically
-            injection = Thread(target=self._inject, kwargs={'injection_duration': 0.2, 'polarity': polarity})
+            injection = Thread(target=self._inject, kwargs={'injection_duration': 0.2, 'polarity': pol})
             readings = Thread(target=self._read_values)
             readings.start()
             injection.start()