diff --git a/dev/test_3_mux_2024.py b/dev/test_3_mux_2024.py
index aa2a9d41530af5c93b5ec401e383dff723a7e8e7..c591b04fa0552ecb879ad94c2982ea262b5e6f47 100644
--- a/dev/test_3_mux_2024.py
+++ b/dev/test_3_mux_2024.py
@@ -59,5 +59,5 @@ if within_ohmpi:
     # k._hw._plot_readings()
     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')
+    # plot_exec_log('ohmpi/logs/exec.log')
 change_config('../configs/config_default.py', verbose=False)
diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index d0f08e8728d362d4eebc11358a38bdb75003bd57..e2316410f1968689b6a55a48b39f677042045132 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -313,7 +313,7 @@ class OhmPiHardware:
             polarity = 1
         return vab, polarity, rab
 
-    def _plot_readings(self):
+    def _plot_readings(self, save_fig=False):
         # Plot graphs
         fig, ax = plt.subplots(nrows=3, sharex=True)
         ax[0].plot(self.readings[:, 0], self.readings[:, 3], '-r', marker='.', label='iab')
@@ -323,7 +323,10 @@ class OhmPiHardware:
         ax[2].plot(self.readings[:, 0], self.readings[:, 2], '-g', marker='.', label='polarity')
         ax[2].set_ylabel('polarity [-]')
         fig.legend()
-        plt.show()
+        if save_fig:
+            fig.savefig(f'figures/test.png')
+        else:
+            plt.show()
 
     def calibrate_rx_bias(self):
         self.rx._bias += (np.mean(self.readings[self.readings[:, 2] == 1, 4])
diff --git a/ohmpi/ohmpi.py b/ohmpi/ohmpi.py
index 322a9c90a5887ffaf5820c1920301285e956957f..ae66f806a3a917baf18454fdbc388f3ae02a2de0 100644
--- a/ohmpi/ohmpi.py
+++ b/ohmpi/ohmpi.py
@@ -460,7 +460,7 @@ class OhmPi(object):
                 delay = 0.
             x = np.where((self._hw.readings[:, 0] >= delay) & (self._hw.readings[:, 2] != 0))
             R = np.mean(self._hw.readings[x, 2]*self._hw.readings[x, 4])/np.median(self._hw.readings[x, 3])
-            R_std = 100. * np.std(self._hw.readings[x, 2] * (self._hw.readings[x, 4] - self._hw.sp) / self._hw.readings[x, 3])/R
+            R_std = 100. * np.std(self._hw.readings[x, 2] * (self._hw.readings[x, 4] - self._hw.sp) / self._hw.readings[x, 3]) / R
             d = {
                 "time": datetime.now().isoformat(),
                 "A": quad[0],