diff --git a/doc/source/V2_00.rst b/doc/source/V2_00.rst
index 907cb3aba651c8e6e3e682904fa5114e21e310bd..a8365ebd50afeeb6318318d95ed457c9d948688d 100644
--- a/doc/source/V2_00.rst
+++ b/doc/source/V2_00.rst
@@ -73,6 +73,7 @@ Ohmpi 2 step by step
    Ohmpi_V2_00/V2_00_step_02
    Ohmpi_V2_00/V2_00_step_03
    Ohmpi_V2_00/V2_00_step_04
+   Ohmpi_V2_00/V2_00_usage
 
 
 
diff --git a/ohmpi.py b/ohmpi.py
index ae3d891d818333a84eb9c15978fc5274288deac1..59f32c08b597c774dbe114ce044d7ea856690f14 100644
--- a/ohmpi.py
+++ b/ohmpi.py
@@ -527,31 +527,34 @@ class OhmPi(object):
 
         
     def run_measurement(self, quad=[1, 2, 3, 4], nb_stack=None, injection_duration=None,
-                        tx_volt=5, autogain=True, best_tx_injtime=0.1, strategy='constant'):
+                        autogain=True, strategy='constant', tx_volt=5, best_tx_injtime=0.1):
         """Do a 4 electrode measurement and measure transfer resistance obtained.
 
         Parameters
         ----------
         quad : list of int
-            Quadrupole to measure.
+            Quadrupole to measure, just for labelling. Only switch_mux_on/off
+            really create the route to the electrodes.
         nb_stack : int, optional
             Number of stacks. A stacl is considered two half-cycles (one
             positive, one negative).
         injection_duration : int, optional
             Injection time in seconds.
-        tx_volt : float, optional
-            If specified, voltage will be imposed. If 0, we will look 
-            for the best voltage. If a best Tx cannot be found, no
-            measurement will be taken and values will be NaN.
         autogain : bool, optional
             If True, will adapt the gain of the ADS1115 to maximize the
             resolution of the reading.
         strategy : str, optional
-            If we search for best voltage (tx_volt == 0), we can choose
+            (V3.0 only) If we search for best voltage (tx_volt == 0), we can choose
             different strategy:
             - vmin: find lowest voltage that gives us a signal
             - vmax: find max voltage that are in the range
             For a constant value, just set the tx_volt.
+        tx_volt : float, optional
+            (V3.0 only) If specified, voltage will be imposed. If 0, we will look 
+            for the best voltage. If a best Tx cannot be found, no
+            measurement will be taken and values will be NaN.
+        best_tx_injtime : float, optional
+            (V3.0 only) Injection time in seconds used for finding the best voltage.
         """
         # check arguments
         if nb_stack is None:
diff --git a/test.py b/test.py
index e11e2c21c48616191807d1cb33af8d8e72e6ded8..a229a381c854b8c1d66cb91d4e90a91a03b13ac7 100644
--- a/test.py
+++ b/test.py
@@ -11,7 +11,6 @@ seq = np.c_[a, b, m, n]
 k = OhmPi(idps=True)
 k.pardict['injection_duration'] = 0.5
 k.pardict['nb_stack'] = 1
-k.pardict['tx_volt'] = 0
 k.pardict['nbr_meas'] = 1
 #k.sequence = seq
 #k.reset_mux()