diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index a81147d61861d63eb7f91af5dc6e21d22aa0535a..33aba8ae531adbaab4876b2a21630402c1377182 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -129,7 +129,7 @@ class OhmPiHardware:
                               self.rx.voltage])
             sample += 1
             sleep_time = self._start_time + datetime.timedelta(seconds=sample * sampling_rate / 1000) - lap
-            time.sleep(np.max([0, sleep_time.total_seconds()]))
+            time.sleep(np.max([0.001, sleep_time.total_seconds()]))
         self.readings = np.array(_readings)
         self._pulse += 1
 
diff --git a/uml_diagrams/classes_uml_ohmpi.dot b/uml_diagrams/classes_uml_ohmpi.dot
index b310aa483ca5a3145dea234295d9cd678aa27938..c482b8c97b233760a25b84cbb14073b22cdbe399 100644
--- a/uml_diagrams/classes_uml_ohmpi.dot
+++ b/uml_diagrams/classes_uml_ohmpi.dot
@@ -10,7 +10,7 @@ rankdir=BT
 "6" [label="{Mux|addresses : dict\l|reset()\lswitch_one(elec, role, state)\l}", shape="record"];
 "7" [label="{MuxAbstract|addresses\lbarrier\lboard_id\lboard_name\lcabling : dict\lctl\lexec_logger : RootLogger, NoneType\lsoh_logger : RootLogger, NoneType\l|reset()\lswitch(elec_dict, state)\lswitch_one(elec, role, state)\ltest(elec_dict, activation_time)\l}", shape="record"];
 "8" [label="{MyServer|\l|do_POST()\l}", shape="record"];
-"9" [label="{OhmPi|cmd_id : NoneType\lcontroller : NoneType\ldata_logger : RootLogger, NoneType\lexec_logger : NoneType, RootLogger\lid : str\lmqtt : bool\lnb_samples : int\lon_pi : bool, NoneType\lsequence\lsequence : ndarray, NoneType\lsettings : dict\lsoh_logger : RootLogger, NoneType\lstatus : str\lthread : NoneType, Thread\l|append_and_save(filename, last_measurement, cmd_id)\lget_data(survey_names, cmd_id)\lget_deprecated_methods(cls)\linterrupt(cmd_id)\lload_sequence(filename, cmd_id)\lquit(cmd_id)\lremove_data(cmd_id)\lreset_mux(cmd_id)\lrestart(cmd_id)\lrs_check(tx_volt, cmd_id)\lrun_measurement(quad, nb_stack, injection_duration, autogain, strategy, tx_volt, best_tx_injtime, cmd_id)\lrun_multiple_sequences(cmd_id, sequence_delay, nb_meas)\lrun_sequence(cmd_id)\lrun_sequence_async(cmd_id)\lset_sequence(sequence, cmd_id)\lswitch_mux_off(quadrupole, cmd_id)\lswitch_mux_on(quadrupole, cmd_id)\ltest_mux(activation_time, mux_id, cmd_id)\lupdate_settings(settings, cmd_id)\l}", shape="record"];
+"9" [label="{OhmPi|cmd_id : NoneType\lcontroller : NoneType\ldata_logger : RootLogger, NoneType\lexec_logger : RootLogger, NoneType\lid : str\lmqtt : bool\lnb_samples : int\lon_pi : bool, NoneType\lsequence\lsequence : ndarray, NoneType\lsettings : dict\lsoh_logger : RootLogger, NoneType\lstatus : str\lthread : NoneType, Thread\l|append_and_save(filename, last_measurement, cmd_id)\lget_data(survey_names, cmd_id)\lget_deprecated_methods(cls)\linterrupt(cmd_id)\lload_sequence(filename, cmd_id)\lquit(cmd_id)\lremove_data(cmd_id)\lreset_mux(cmd_id)\lrestart(cmd_id)\lrs_check(tx_volt, cmd_id)\lrun_measurement(quad, nb_stack, injection_duration, autogain, strategy, tx_volt, best_tx_injtime, cmd_id)\lrun_multiple_sequences(cmd_id, sequence_delay, nb_meas)\lrun_sequence(cmd_id)\lrun_sequence_async(cmd_id)\lset_sequence(sequence, cmd_id)\lswitch_mux_off(quadrupole, cmd_id)\lswitch_mux_on(quadrupole, cmd_id)\ltest_mux(activation_time, mux_id, cmd_id)\lupdate_settings(settings, cmd_id)\l}", shape="record"];
 "10" [label="{OhmPiHardware|ctl\ldata_logger : NoneType, RootLogger\lexec_logger : RootLogger, NoneType\lmux_barrier : Barrier\lmux_boards\lpulses\lpwr\lreadings : ndarray\lrx\lsoh_logger : RootLogger, NoneType\lsp\ltx\ltx_sync : Event\l|reset_mux()\lswitch_mux(electrodes, roles, state)\ltest_mux(channel, activation_time)\lvab_square_wave(vab, cycle_length, sampling_rate, cycles, polarity, append)\l}", shape="record"];
 "11" [label="{Pwr|current\lvoltage\lvoltage_adjustable : bool\l|turn_off()\lturn_on()\l}", shape="record"];
 "12" [label="{PwrAbstract|board_name\lcurrent\lexec_logger : RootLogger, NoneType\lsoh_logger : NoneType, RootLogger\lvoltage\lvoltage_adjustable\l|turn_off()\lturn_on()\l}", shape="record"];
diff --git a/uml_diagrams/classes_uml_ohmpi.dot.png b/uml_diagrams/classes_uml_ohmpi.dot.png
index 754776015e66c92c98bd3716813dbbd7027ab732..2b0acf4cd90e158c58858bea56a60c84bb1e17e9 100644
Binary files a/uml_diagrams/classes_uml_ohmpi.dot.png and b/uml_diagrams/classes_uml_ohmpi.dot.png differ
diff --git a/update_uml.sh b/update_uml.sh
old mode 100644
new mode 100755